# NullCipher
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels)
# NullCipher
```
open class NullCipher : Cipher
```
|---|---|----------------------------------------------------------------------------------------------------|
| [kotlin.Any](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-any/index.html) |||
| ↳ | [javax.crypto.Cipher](https://developer.android.com/reference/kotlin/javax/crypto/Cipher) ||
| | ↳ | [javax.crypto.NullCipher](https://developer.android.com/reference/kotlin/javax/crypto/NullCipher#) |
The NullCipher class is a class that provides an "identity cipher" -- one that does not transform the plain text. As a consequence, the ciphertext is identical to the plaintext. All initialization methods do nothing, while the blocksize is set to 1 byte.
## Summary
| Inherited constants ||
|---|---|
| From class[Cipher](https://developer.android.com/reference/kotlin/javax/crypto/Cipher) |----------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html) | [DECRYPT_MODE](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#DECRYPT_MODE:kotlin.Int)
Constant used to initialize cipher to decryption mode.
| | [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html) | [ENCRYPT_MODE](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#ENCRYPT_MODE:kotlin.Int)
Constant used to initialize cipher to encryption mode.
| | [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html) | [PRIVATE_KEY](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#PRIVATE_KEY:kotlin.Int)
Constant used to indicate the to-be-unwrapped key is a "private key".
| | [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html) | [PUBLIC_KEY](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#PUBLIC_KEY:kotlin.Int)
Constant used to indicate the to-be-unwrapped key is a "public key".
| | [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html) | [SECRET_KEY](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#SECRET_KEY:kotlin.Int)
Constant used to indicate the to-be-unwrapped key is a "secret key".
| | [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html) | [UNWRAP_MODE](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#UNWRAP_MODE:kotlin.Int)
Constant used to initialize cipher to key-unwrapping mode.
| | [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html) | [WRAP_MODE](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#WRAP_MODE:kotlin.Int)
Constant used to initialize cipher to key-wrapping mode.
| ||
| Public constructors ||
|------------------------------------------------------------------------------------------------------------------------------------|---|
| [NullCipher](https://developer.android.com/reference/kotlin/javax/crypto/NullCipher#NullCipher())`()` Creates a NullCipher object. |
| Inherited functions ||
|---|---|
| From class[Cipher](https://developer.android.com/reference/kotlin/javax/crypto/Cipher) |---------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | [ByteArray](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-byte-array/index.html)! | [doFinal](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#doFinal())`()`
Finishes a multiple-part encryption or decryption operation, depending on how this cipher was initialized. Input data that may have been buffered during a previous`update`operation is processed, with padding (if requested) being applied. If an AEAD mode such as GCM/CCM is being used, the authentication tag is appended in the case of encryption, or verified in the case of decryption. The result is stored in a new buffer. Upon finishing, this method resets this cipher object to the state it was in when previously initialized via a call to`init`. That is, the object is reset and available to encrypt or decrypt (depending on the operation mode that was specified in the call to`init`) more data. Note: if any exception is thrown, this cipher object may need to be reset before it can be used again.
| | [ByteArray](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-byte-array/index.html)! | [doFinal](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#doFinal(kotlin.ByteArray))`(`input:` `[ByteArray](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-byte-array/index.html)!`)`
Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation. The data is encrypted or decrypted, depending on how this cipher was initialized. The bytes in the`input`buffer, and any input bytes that may have been buffered during a previous`update`operation, are processed, with padding (if requested) being applied. If an AEAD mode such as GCM/CCM is being used, the authentication tag is appended in the case of encryption, or verified in the case of decryption. The result is stored in a new buffer. Upon finishing, this method resets this cipher object to the state it was in when previously initialized via a call to`init`. That is, the object is reset and available to encrypt or decrypt (depending on the operation mode that was specified in the call to`init`) more data. Note: if any exception is thrown, this cipher object may need to be reset before it can be used again.
| | [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html) | [doFinal](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#doFinal(kotlin.ByteArray,%20kotlin.Int))`(`output:` `[ByteArray](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-byte-array/index.html)!`, `outputOffset:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`)`
Finishes a multiple-part encryption or decryption operation, depending on how this cipher was initialized. Input data that may have been buffered during a previous`update`operation is processed, with padding (if requested) being applied. If an AEAD mode such as GCM/CCM is being used, the authentication tag is appended in the case of encryption, or verified in the case of decryption. The result is stored in the`output`buffer, starting at`outputOffset`inclusive. If the`output`buffer is too small to hold the result, a`ShortBufferException`is thrown. In this case, repeat this call with a larger output buffer. Use[getOutputSize](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#getOutputSize(kotlin.Int))to determine how big the output buffer should be. Upon finishing, this method resets this cipher object to the state it was in when previously initialized via a call to`init`. That is, the object is reset and available to encrypt or decrypt (depending on the operation mode that was specified in the call to`init`) more data. Note: if any exception is thrown, this cipher object may need to be reset before it can be used again.
| | [ByteArray](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-byte-array/index.html)! | [doFinal](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#doFinal(kotlin.ByteArray,%20kotlin.Int,%20kotlin.Int))`(`input:` `[ByteArray](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-byte-array/index.html)!`, `inputOffset:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`, `inputLen:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`)`
Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation. The data is encrypted or decrypted, depending on how this cipher was initialized. The first`inputLen`bytes in the`input`buffer, starting at`inputOffset`inclusive, and any input bytes that may have been buffered during a previous`update`operation, are processed, with padding (if requested) being applied. If an AEAD mode such as GCM/CCM is being used, the authentication tag is appended in the case of encryption, or verified in the case of decryption. The result is stored in a new buffer. Upon finishing, this method resets this cipher object to the state it was in when previously initialized via a call to`init`. That is, the object is reset and available to encrypt or decrypt (depending on the operation mode that was specified in the call to`init`) more data. Note: if any exception is thrown, this cipher object may need to be reset before it can be used again.
| | [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html) | [doFinal](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#doFinal(kotlin.ByteArray,%20kotlin.Int,%20kotlin.Int,%20kotlin.ByteArray))`(`input:` `[ByteArray](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-byte-array/index.html)!`, `inputOffset:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`, `inputLen:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`, `output:` `[ByteArray](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-byte-array/index.html)!`)`
Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation. The data is encrypted or decrypted, depending on how this cipher was initialized. The first`inputLen`bytes in the`input`buffer, starting at`inputOffset`inclusive, and any input bytes that may have been buffered during a previous`update`operation, are processed, with padding (if requested) being applied. If an AEAD mode such as GCM/CCM is being used, the authentication tag is appended in the case of encryption, or verified in the case of decryption. The result is stored in the`output`buffer. If the`output`buffer is too small to hold the result, a`ShortBufferException`is thrown. In this case, repeat this call with a larger output buffer. Use[getOutputSize](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#getOutputSize(kotlin.Int))to determine how big the output buffer should be. Upon finishing, this method resets this cipher object to the state it was in when previously initialized via a call to`init`. That is, the object is reset and available to encrypt or decrypt (depending on the operation mode that was specified in the call to`init`) more data. Note: if any exception is thrown, this cipher object may need to be reset before it can be used again. Note: this method should be copy-safe, which means the`input`and`output`buffers can reference the same byte array and no unprocessed input data is overwritten when the result is copied into the output buffer.
| | [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html) | [doFinal](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#doFinal(kotlin.ByteArray,%20kotlin.Int,%20kotlin.Int,%20kotlin.ByteArray,%20kotlin.Int))`(`input:` `[ByteArray](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-byte-array/index.html)!`, `inputOffset:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`, `inputLen:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`, `output:` `[ByteArray](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-byte-array/index.html)!`, `outputOffset:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`)`
Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation. The data is encrypted or decrypted, depending on how this cipher was initialized. The first`inputLen`bytes in the`input`buffer, starting at`inputOffset`inclusive, and any input bytes that may have been buffered during a previous`update`operation, are processed, with padding (if requested) being applied. If an AEAD mode such as GCM/CCM is being used, the authentication tag is appended in the case of encryption, or verified in the case of decryption. The result is stored in the`output`buffer, starting at`outputOffset`inclusive. If the`output`buffer is too small to hold the result, a`ShortBufferException`is thrown. In this case, repeat this call with a larger output buffer. Use[getOutputSize](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#getOutputSize(kotlin.Int))to determine how big the output buffer should be. Upon finishing, this method resets this cipher object to the state it was in when previously initialized via a call to`init`. That is, the object is reset and available to encrypt or decrypt (depending on the operation mode that was specified in the call to`init`) more data. Note: if any exception is thrown, this cipher object may need to be reset before it can be used again. Note: this method should be copy-safe, which means the`input`and`output`buffers can reference the same byte array and no unprocessed input data is overwritten when the result is copied into the output buffer.
| | [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html) | [doFinal](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#doFinal(java.nio.ByteBuffer,%20java.nio.ByteBuffer))`(`input:` `[ByteBuffer](https://developer.android.com/reference/kotlin/java/nio/ByteBuffer.html#)!`, `output:` `[ByteBuffer](https://developer.android.com/reference/kotlin/java/nio/ByteBuffer.html#)!`)`
Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation. The data is encrypted or decrypted, depending on how this cipher was initialized. All`input.remaining()`bytes starting at`input.position()`are processed. If an AEAD mode such as GCM/CCM is being used, the authentication tag is appended in the case of encryption, or verified in the case of decryption. The result is stored in the output buffer. Upon return, the input buffer's position will be equal to its limit; its limit will not have changed. The output buffer's position will have advanced by n, where n is the value returned by this method; the output buffer's limit will not have changed. If`output.remaining()`bytes are insufficient to hold the result, a`ShortBufferException`is thrown. In this case, repeat this call with a larger output buffer. Use[getOutputSize](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#getOutputSize(kotlin.Int))to determine how big the output buffer should be. Upon finishing, this method resets this cipher object to the state it was in when previously initialized via a call to`init`. That is, the object is reset and available to encrypt or decrypt (depending on the operation mode that was specified in the call to`init`) more data. Note: if any exception is thrown, this cipher object may need to be reset before it can be used again. Note: this method should be copy-safe, which means the`input`and`output`buffers can reference the same byte array and no unprocessed input data is overwritten when the result is copied into the output buffer.
| | [String](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-string/index.html)! | [getAlgorithm](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#getAlgorithm())`()`
Returns the algorithm name of this`Cipher`object. This is the same name that was specified in one of the`getInstance`calls that created this`Cipher`object..
| | [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html) | [getBlockSize](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#getBlockSize())`()`
Returns the block size (in bytes).
| | [ExemptionMechanism](https://developer.android.com/reference/kotlin/javax/crypto/ExemptionMechanism)! | [getExemptionMechanism](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#getExemptionMechanism())`()`
Returns the exemption mechanism object used with this cipher.
| | [ByteArray](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-byte-array/index.html)! | [getIV](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#getIV())`()`
Returns the initialization vector (IV) in a new buffer. This is useful in the case where a random IV was created, or in the context of password-based encryption or decryption, where the IV is derived from a user-supplied password.
| | [Cipher](https://developer.android.com/reference/kotlin/javax/crypto/Cipher)! | [getInstance](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#getInstance(kotlin.String))`(`transformation:` `[String](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-string/index.html)!`)`
Returns a`Cipher`object that implements the specified transformation. This method traverses the list of registered security Providers, starting with the most preferred Provider. A new Cipher object encapsulating the CipherSpi implementation from the first Provider that supports the specified algorithm is returned. Note that the list of registered providers may be retrieved via the[Security.getProviders()](https://developer.android.com/reference/kotlin/java/security/Security.html#getProviders())method.
| | [Cipher](https://developer.android.com/reference/kotlin/javax/crypto/Cipher)! | [getInstance](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#getInstance(kotlin.String,%20kotlin.String))`(`transformation:` `[String](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-string/index.html)!`, `provider:` `[String](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-string/index.html)!`)`
Returns a`Cipher`object that implements the specified transformation. A new Cipher object encapsulating the CipherSpi implementation from the specified provider is returned. The specified provider must be registered in the security provider list. Note that the list of registered providers may be retrieved via the[Security.getProviders()](https://developer.android.com/reference/kotlin/java/security/Security.html#getProviders())method.
| | [Cipher](https://developer.android.com/reference/kotlin/javax/crypto/Cipher)! | [getInstance](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#getInstance(kotlin.String,%20java.security.Provider))`(`transformation:` `[String](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-string/index.html)!`, `provider:` `[Provider](https://developer.android.com/reference/kotlin/java/security/Provider.html#)!`)`
Returns a`Cipher`object that implements the specified transformation. A new Cipher object encapsulating the CipherSpi implementation from the specified Provider object is returned. Note that the specified Provider object does not have to be registered in the provider list.
| | [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html) | [getMaxAllowedKeyLength](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#getMaxAllowedKeyLength(kotlin.String))`(`transformation:` `[String](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-string/index.html)!`)`
Returns the maximum key length for the specified transformation according to the installed JCE jurisdiction policy files. If JCE unlimited strength jurisdiction policy files are installed, Integer.MAX_VALUE will be returned. For more information on default key size in JCE jurisdiction policy files, please see Appendix E in the[Java Cryptography Architecture Reference Guide](https://docs.oracle.com/javase/8/docs/technotes/guides/security/crypto/CryptoSpec.html#AppC).
| | [AlgorithmParameterSpec](https://developer.android.com/reference/kotlin/java/security/spec/AlgorithmParameterSpec.html#)! | [getMaxAllowedParameterSpec](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#getMaxAllowedParameterSpec(kotlin.String))`(`transformation:` `[String](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-string/index.html)!`)`
Returns an AlgorithmParameterSpec object which contains the maximum cipher parameter value according to the jurisdiction policy file. If JCE unlimited strength jurisdiction policy files are installed or there is no maximum limit on the parameters for the specified transformation in the policy file, null will be returned.
| | [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html) | [getOutputSize](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#getOutputSize(kotlin.Int))`(`inputLen:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`)`
Returns the length in bytes that an output buffer would need to be in order to hold the result of the next`update`or`doFinal`operation, given the input length`inputLen`(in bytes). This call takes into account any unprocessed (buffered) data from a previous`update`call, padding, and AEAD tagging. The actual output length of the next`update`or`doFinal`call may be smaller than the length returned by this method.
| | [AlgorithmParameters](https://developer.android.com/reference/kotlin/java/security/AlgorithmParameters.html#)! | [getParameters](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#getParameters())`()`
Returns the parameters used with this cipher. The returned parameters may be the same that were used to initialize this cipher, or may contain a combination of default and random parameter values used by the underlying cipher implementation if this cipher requires algorithm parameters but was not initialized with any.
| | [Provider](https://developer.android.com/reference/kotlin/java/security/Provider.html#)! | [getProvider](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#getProvider())`()`
Returns the provider of this`Cipher`object.
| | [Unit](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-unit/index.html) | [init](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#init(kotlin.Int,%20java.security.cert.Certificate))`(`opmode:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`, `certificate:` `[Certificate](https://developer.android.com/reference/kotlin/java/security/cert/Certificate.html#)!`)`
Initializes this cipher with the public key from the given certificate. The cipher is initialized for one of the following four operations: encryption, decryption, key wrapping or key unwrapping, depending on the value of`opmode`. If the certificate is of type X.509 and has a*key usage* extension field marked as critical, and the value of the*key usage* extension field implies that the public key in the certificate and its corresponding private key are not supposed to be used for the operation represented by the value of`opmode`, an`InvalidKeyException`is thrown. If this cipher requires any algorithm parameters that cannot be derived from the public key in the given certificate, the underlying cipher implementation is supposed to generate the required parameters itself (using provider-specific default or random values) if it is being initialized for encryption or key wrapping, and raise an` InvalidKeyException`if it is being initialized for decryption or key unwrapping. The generated parameters can be retrieved using[getParameters](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#getParameters())or[getIV](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#getIV())(if the parameter is an IV). If this cipher requires algorithm parameters that cannot be derived from the input parameters, and there are no reasonable provider-specific default values, initialization will necessarily fail. If this cipher (including its underlying feedback or padding scheme) requires any random bytes (e.g., for parameter generation), it will get them using the`SecureRandom`implementation of the highest-priority installed provider as the source of randomness. (If none of the installed providers supply an implementation of SecureRandom, a system-provided source of randomness will be used.) Note that when a Cipher object is initialized, it loses all previously-acquired state. In other words, initializing a Cipher is equivalent to creating a new instance of that Cipher and initializing it.
| | [Unit](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-unit/index.html) | [init](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#init(kotlin.Int,%20java.security.cert.Certificate,%20java.security.SecureRandom))`(`opmode:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`, `certificate:` `[Certificate](https://developer.android.com/reference/kotlin/java/security/cert/Certificate.html#)!`, `random:` `[SecureRandom](https://developer.android.com/reference/kotlin/java/security/SecureRandom.html#)!`)`
Initializes this cipher with the public key from the given certificate and a source of randomness. The cipher is initialized for one of the following four operations: encryption, decryption, key wrapping or key unwrapping, depending on the value of`opmode`. If the certificate is of type X.509 and has a*key usage* extension field marked as critical, and the value of the*key usage* extension field implies that the public key in the certificate and its corresponding private key are not supposed to be used for the operation represented by the value of`opmode`, an`InvalidKeyException`is thrown. If this cipher requires any algorithm parameters that cannot be derived from the public key in the given`certificate`, the underlying cipher implementation is supposed to generate the required parameters itself (using provider-specific default or random values) if it is being initialized for encryption or key wrapping, and raise an`InvalidKeyException`if it is being initialized for decryption or key unwrapping. The generated parameters can be retrieved using[getParameters](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#getParameters())or[getIV](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#getIV())(if the parameter is an IV). If this cipher requires algorithm parameters that cannot be derived from the input parameters, and there are no reasonable provider-specific default values, initialization will necessarily fail. If this cipher (including its underlying feedback or padding scheme) requires any random bytes (e.g., for parameter generation), it will get them from`random`. Note that when a Cipher object is initialized, it loses all previously-acquired state. In other words, initializing a Cipher is equivalent to creating a new instance of that Cipher and initializing it.
| | [Unit](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-unit/index.html) | [init](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#init(kotlin.Int,%20java.security.Key))`(`opmode:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`, `key:` `[Key](https://developer.android.com/reference/kotlin/java/security/Key.html#)!`)`
Initializes this cipher with a key. The cipher is initialized for one of the following four operations: encryption, decryption, key wrapping or key unwrapping, depending on the value of`opmode`. If this cipher requires any algorithm parameters that cannot be derived from the given`key`, the underlying cipher implementation is supposed to generate the required parameters itself (using provider-specific default or random values) if it is being initialized for encryption or key wrapping, and raise an`InvalidKeyException`if it is being initialized for decryption or key unwrapping. The generated parameters can be retrieved using[getParameters](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#getParameters())or[getIV](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#getIV())(if the parameter is an IV). If this cipher requires algorithm parameters that cannot be derived from the input parameters, and there are no reasonable provider-specific default values, initialization will necessarily fail. If this cipher (including its underlying feedback or padding scheme) requires any random bytes (e.g., for parameter generation), it will get them using the[java.security.SecureRandom](https://developer.android.com/reference/kotlin/java/security/SecureRandom.html#)implementation of the highest-priority installed provider as the source of randomness. (If none of the installed providers supply an implementation of SecureRandom, a system-provided source of randomness will be used.) Note that when a Cipher object is initialized, it loses all previously-acquired state. In other words, initializing a Cipher is equivalent to creating a new instance of that Cipher and initializing it.
| | [Unit](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-unit/index.html) | [init](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#init(kotlin.Int,%20java.security.Key,%20java.security.AlgorithmParameters))`(`opmode:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`, `key:` `[Key](https://developer.android.com/reference/kotlin/java/security/Key.html#)!`, `params:` `[AlgorithmParameters](https://developer.android.com/reference/kotlin/java/security/AlgorithmParameters.html#)!`)`
Initializes this cipher with a key and a set of algorithm parameters. The cipher is initialized for one of the following four operations: encryption, decryption, key wrapping or key unwrapping, depending on the value of`opmode`. If this cipher requires any algorithm parameters and`params`is null, the underlying cipher implementation is supposed to generate the required parameters itself (using provider-specific default or random values) if it is being initialized for encryption or key wrapping, and raise an`InvalidAlgorithmParameterException`if it is being initialized for decryption or key unwrapping. The generated parameters can be retrieved using[getParameters](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#getParameters())or[getIV](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#getIV())(if the parameter is an IV). If this cipher requires algorithm parameters that cannot be derived from the input parameters, and there are no reasonable provider-specific default values, initialization will necessarily fail. If this cipher (including its underlying feedback or padding scheme) requires any random bytes (e.g., for parameter generation), it will get them using the[java.security.SecureRandom](https://developer.android.com/reference/kotlin/java/security/SecureRandom.html#)implementation of the highest-priority installed provider as the source of randomness. (If none of the installed providers supply an implementation of SecureRandom, a system-provided source of randomness will be used.) Note that when a Cipher object is initialized, it loses all previously-acquired state. In other words, initializing a Cipher is equivalent to creating a new instance of that Cipher and initializing it.
| | [Unit](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-unit/index.html) | [init](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#init(kotlin.Int,%20java.security.Key,%20java.security.AlgorithmParameters,%20java.security.SecureRandom))`(`opmode:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`, `key:` `[Key](https://developer.android.com/reference/kotlin/java/security/Key.html#)!`, `params:` `[AlgorithmParameters](https://developer.android.com/reference/kotlin/java/security/AlgorithmParameters.html#)!`, `random:` `[SecureRandom](https://developer.android.com/reference/kotlin/java/security/SecureRandom.html#)!`)`
Initializes this cipher with a key, a set of algorithm parameters, and a source of randomness. The cipher is initialized for one of the following four operations: encryption, decryption, key wrapping or key unwrapping, depending on the value of`opmode`. If this cipher requires any algorithm parameters and`params`is null, the underlying cipher implementation is supposed to generate the required parameters itself (using provider-specific default or random values) if it is being initialized for encryption or key wrapping, and raise an`InvalidAlgorithmParameterException`if it is being initialized for decryption or key unwrapping. The generated parameters can be retrieved using[getParameters](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#getParameters())or[getIV](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#getIV())(if the parameter is an IV). If this cipher requires algorithm parameters that cannot be derived from the input parameters, and there are no reasonable provider-specific default values, initialization will necessarily fail. If this cipher (including its underlying feedback or padding scheme) requires any random bytes (e.g., for parameter generation), it will get them from`random`. Note that when a Cipher object is initialized, it loses all previously-acquired state. In other words, initializing a Cipher is equivalent to creating a new instance of that Cipher and initializing it.
| | [Unit](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-unit/index.html) | [init](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#init(kotlin.Int,%20java.security.Key,%20java.security.SecureRandom))`(`opmode:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`, `key:` `[Key](https://developer.android.com/reference/kotlin/java/security/Key.html#)!`, `random:` `[SecureRandom](https://developer.android.com/reference/kotlin/java/security/SecureRandom.html#)!`)`
Initializes this cipher with a key and a source of randomness. The cipher is initialized for one of the following four operations: encryption, decryption, key wrapping or key unwrapping, depending on the value of`opmode`. If this cipher requires any algorithm parameters that cannot be derived from the given`key`, the underlying cipher implementation is supposed to generate the required parameters itself (using provider-specific default or random values) if it is being initialized for encryption or key wrapping, and raise an`InvalidKeyException`if it is being initialized for decryption or key unwrapping. The generated parameters can be retrieved using[getParameters](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#getParameters())or[getIV](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#getIV())(if the parameter is an IV). If this cipher requires algorithm parameters that cannot be derived from the input parameters, and there are no reasonable provider-specific default values, initialization will necessarily fail. If this cipher (including its underlying feedback or padding scheme) requires any random bytes (e.g., for parameter generation), it will get them from`random`. Note that when a Cipher object is initialized, it loses all previously-acquired state. In other words, initializing a Cipher is equivalent to creating a new instance of that Cipher and initializing it.
| | [Unit](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-unit/index.html) | [init](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#init(kotlin.Int,%20java.security.Key,%20java.security.spec.AlgorithmParameterSpec))`(`opmode:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`, `key:` `[Key](https://developer.android.com/reference/kotlin/java/security/Key.html#)!`, `params:` `[AlgorithmParameterSpec](https://developer.android.com/reference/kotlin/java/security/spec/AlgorithmParameterSpec.html#)!`)`
Initializes this cipher with a key and a set of algorithm parameters. The cipher is initialized for one of the following four operations: encryption, decryption, key wrapping or key unwrapping, depending on the value of`opmode`. If this cipher requires any algorithm parameters and`params`is null, the underlying cipher implementation is supposed to generate the required parameters itself (using provider-specific default or random values) if it is being initialized for encryption or key wrapping, and raise an`InvalidAlgorithmParameterException`if it is being initialized for decryption or key unwrapping. The generated parameters can be retrieved using[getParameters](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#getParameters())or[getIV](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#getIV())(if the parameter is an IV). If this cipher requires algorithm parameters that cannot be derived from the input parameters, and there are no reasonable provider-specific default values, initialization will necessarily fail. If this cipher (including its underlying feedback or padding scheme) requires any random bytes (e.g., for parameter generation), it will get them using the[java.security.SecureRandom](https://developer.android.com/reference/kotlin/java/security/SecureRandom.html#)implementation of the highest-priority installed provider as the source of randomness. (If none of the installed providers supply an implementation of SecureRandom, a system-provided source of randomness will be used.) Note that when a Cipher object is initialized, it loses all previously-acquired state. In other words, initializing a Cipher is equivalent to creating a new instance of that Cipher and initializing it.
| | [Unit](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-unit/index.html) | [init](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#init(kotlin.Int,%20java.security.Key,%20java.security.spec.AlgorithmParameterSpec,%20java.security.SecureRandom))`(`opmode:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`, `key:` `[Key](https://developer.android.com/reference/kotlin/java/security/Key.html#)!`, `params:` `[AlgorithmParameterSpec](https://developer.android.com/reference/kotlin/java/security/spec/AlgorithmParameterSpec.html#)!`, `random:` `[SecureRandom](https://developer.android.com/reference/kotlin/java/security/SecureRandom.html#)!`)`
Initializes this cipher with a key, a set of algorithm parameters, and a source of randomness. The cipher is initialized for one of the following four operations: encryption, decryption, key wrapping or key unwrapping, depending on the value of`opmode`. If this cipher requires any algorithm parameters and`params`is null, the underlying cipher implementation is supposed to generate the required parameters itself (using provider-specific default or random values) if it is being initialized for encryption or key wrapping, and raise an`InvalidAlgorithmParameterException`if it is being initialized for decryption or key unwrapping. The generated parameters can be retrieved using[getParameters](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#getParameters())or[getIV](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#getIV())(if the parameter is an IV). If this cipher requires algorithm parameters that cannot be derived from the input parameters, and there are no reasonable provider-specific default values, initialization will necessarily fail. If this cipher (including its underlying feedback or padding scheme) requires any random bytes (e.g., for parameter generation), it will get them from`random`. Note that when a Cipher object is initialized, it loses all previously-acquired state. In other words, initializing a Cipher is equivalent to creating a new instance of that Cipher and initializing it.
| | [Key](https://developer.android.com/reference/kotlin/java/security/Key.html#)! | [unwrap](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#unwrap(kotlin.ByteArray,%20kotlin.String,%20kotlin.Int))`(`wrappedKey:` `[ByteArray](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-byte-array/index.html)!`, `wrappedKeyAlgorithm:` `[String](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-string/index.html)!`, `wrappedKeyType:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`)`
Unwrap a previously wrapped key.
| | [ByteArray](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-byte-array/index.html)! | [update](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#update(kotlin.ByteArray))`(`input:` `[ByteArray](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-byte-array/index.html)!`)`
Continues a multiple-part encryption or decryption operation (depending on how this cipher was initialized), processing another data part. The bytes in the`input`buffer are processed, and the result is stored in a new buffer. If`input`has a length of zero, this method returns`null`.
| | [ByteArray](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-byte-array/index.html)! | [update](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#update(kotlin.ByteArray,%20kotlin.Int,%20kotlin.Int))`(`input:` `[ByteArray](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-byte-array/index.html)!`, `inputOffset:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`, `inputLen:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`)`
Continues a multiple-part encryption or decryption operation (depending on how this cipher was initialized), processing another data part. The first`inputLen`bytes in the`input`buffer, starting at`inputOffset`inclusive, are processed, and the result is stored in a new buffer. If`inputLen`is zero, this method returns`null`.
| | [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html) | [update](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#update(kotlin.ByteArray,%20kotlin.Int,%20kotlin.Int,%20kotlin.ByteArray))`(`input:` `[ByteArray](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-byte-array/index.html)!`, `inputOffset:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`, `inputLen:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`, `output:` `[ByteArray](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-byte-array/index.html)!`)`
Continues a multiple-part encryption or decryption operation (depending on how this cipher was initialized), processing another data part. The first`inputLen`bytes in the`input`buffer, starting at`inputOffset`inclusive, are processed, and the result is stored in the`output`buffer. If the`output`buffer is too small to hold the result, a`ShortBufferException`is thrown. In this case, repeat this call with a larger output buffer. Use[getOutputSize](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#getOutputSize(kotlin.Int))to determine how big the output buffer should be. If`inputLen`is zero, this method returns a length of zero. Note: this method should be copy-safe, which means the`input`and`output`buffers can reference the same byte array and no unprocessed input data is overwritten when the result is copied into the output buffer.
| | [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html) | [update](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#update(kotlin.ByteArray,%20kotlin.Int,%20kotlin.Int,%20kotlin.ByteArray,%20kotlin.Int))`(`input:` `[ByteArray](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-byte-array/index.html)!`, `inputOffset:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`, `inputLen:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`, `output:` `[ByteArray](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-byte-array/index.html)!`, `outputOffset:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`)`
Continues a multiple-part encryption or decryption operation (depending on how this cipher was initialized), processing another data part. The first`inputLen`bytes in the`input`buffer, starting at`inputOffset`inclusive, are processed, and the result is stored in the`output`buffer, starting at`outputOffset`inclusive. If the`output`buffer is too small to hold the result, a`ShortBufferException`is thrown. In this case, repeat this call with a larger output buffer. Use[getOutputSize](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#getOutputSize(kotlin.Int))to determine how big the output buffer should be. If`inputLen`is zero, this method returns a length of zero. Note: this method should be copy-safe, which means the`input`and`output`buffers can reference the same byte array and no unprocessed input data is overwritten when the result is copied into the output buffer.
| | [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html) | [update](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#update(java.nio.ByteBuffer,%20java.nio.ByteBuffer))`(`input:` `[ByteBuffer](https://developer.android.com/reference/kotlin/java/nio/ByteBuffer.html#)!`, `output:` `[ByteBuffer](https://developer.android.com/reference/kotlin/java/nio/ByteBuffer.html#)!`)`
Continues a multiple-part encryption or decryption operation (depending on how this cipher was initialized), processing another data part. All`input.remaining()`bytes starting at`input.position()`are processed. The result is stored in the output buffer. Upon return, the input buffer's position will be equal to its limit; its limit will not have changed. The output buffer's position will have advanced by n, where n is the value returned by this method; the output buffer's limit will not have changed. If`output.remaining()`bytes are insufficient to hold the result, a`ShortBufferException`is thrown. In this case, repeat this call with a larger output buffer. Use[getOutputSize](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#getOutputSize(kotlin.Int))to determine how big the output buffer should be. Note: this method should be copy-safe, which means the`input`and`output`buffers can reference the same block of memory and no unprocessed input data is overwritten when the result is copied into the output buffer.
| | [Unit](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-unit/index.html) | [updateAAD](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#updateAAD(kotlin.ByteArray))`(`src:` `[ByteArray](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-byte-array/index.html)!`)`
Continues a multi-part update of the Additional Authentication Data (AAD). Calls to this method provide AAD to the cipher when operating in modes such as AEAD (GCM/CCM). If this cipher is operating in either GCM or CCM mode, all AAD must be supplied before beginning operations on the ciphertext (via the`update`and`doFinal`methods).
| | [Unit](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-unit/index.html) | [updateAAD](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#updateAAD(kotlin.ByteArray,%20kotlin.Int,%20kotlin.Int))`(`src:` `[ByteArray](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-byte-array/index.html)!`, `offset:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`, `len:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`)`
Continues a multi-part update of the Additional Authentication Data (AAD), using a subset of the provided buffer. Calls to this method provide AAD to the cipher when operating in modes such as AEAD (GCM/CCM). If this cipher is operating in either GCM or CCM mode, all AAD must be supplied before beginning operations on the ciphertext (via the`update`and`doFinal`methods).
| | [Unit](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-unit/index.html) | [updateAAD](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#updateAAD(java.nio.ByteBuffer))`(`src:` `[ByteBuffer](https://developer.android.com/reference/kotlin/java/nio/ByteBuffer.html#)!`)`
Continues a multi-part update of the Additional Authentication Data (AAD). Calls to this method provide AAD to the cipher when operating in modes such as AEAD (GCM/CCM). If this cipher is operating in either GCM or CCM mode, all AAD must be supplied before beginning operations on the ciphertext (via the`update`and`doFinal`methods). All`src.remaining()`bytes starting at`src.position()`are processed. Upon return, the input buffer's position will be equal to its limit; its limit will not have changed.
| | [ByteArray](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-byte-array/index.html)! | [wrap](https://developer.android.com/reference/kotlin/javax/crypto/Cipher#wrap(java.security.Key))`(`key:` `[Key](https://developer.android.com/reference/kotlin/java/security/Key.html#)!`)`
Wrap a key.
| ||
## Public constructors
### NullCipher
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels)
```
NullCipher()
```
Creates a NullCipher object.