# X509Certificate
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
Summary:[Protected Ctors](https://developer.android.com/reference/java/security/cert/X509Certificate#proctors)\|[Methods](https://developer.android.com/reference/java/security/cert/X509Certificate#pubmethods)\|[Inherited Methods](https://developer.android.com/reference/java/security/cert/X509Certificate#inhmethods)
# X509Certificate
`
public
abstract
class
X509Certificate
`
`
``
extends `[Certificate](https://developer.android.com/reference/java/security/cert/Certificate)`
``
implements
`[X509Extension](https://developer.android.com/reference/java/security/cert/X509Extension)`
`
|---|---|------------------------------------|
| [java.lang.Object](https://developer.android.com/reference/java/lang/Object) |||
| ↳ | [java.security.cert.Certificate](https://developer.android.com/reference/java/security/cert/Certificate) ||
| | ↳ | java.security.cert.X509Certificate |
*** ** * ** ***
Abstract class for X.509 certificates. This provides a standard way to access all the attributes of an X.509 certificate.
In June of 1996, the basic X.509 v3 format was completed by ISO/IEC and ANSI X9, which is described below in ASN.1:
```
Certificate ::= SEQUENCE {
tbsCertificate TBSCertificate,
signatureAlgorithm AlgorithmIdentifier,
signature BIT STRING }
```
These certificates are widely used to support authentication and other functionality in Internet security systems. Common applications include Privacy Enhanced Mail (PEM), Transport Layer Security (SSL), code signing for trusted software distribution, and Secure Electronic Transactions (SET).
These certificates are managed and vouched for by*Certificate Authorities*(CAs). CAs are services which create certificates by placing data in the X.509 standard format and then digitally signing that data. CAs act as trusted third parties, making introductions between principals who have no direct knowledge of each other. CA certificates are either signed by themselves, or by some other CA such as a "root" CA.
More information can be found in[RFC 3280: Internet X.509 Public Key Infrastructure Certificate and CRL Profile](http://www.ietf.org/rfc/rfc3280.txt).
The ASN.1 definition of`tbsCertificate`is:
```
TBSCertificate ::= SEQUENCE {
version [0] EXPLICIT Version DEFAULT v1,
serialNumber CertificateSerialNumber,
signature AlgorithmIdentifier,
issuer Name,
validity Validity,
subject Name,
subjectPublicKeyInfo SubjectPublicKeyInfo,
issuerUniqueID [1] IMPLICIT UniqueIdentifier OPTIONAL,
-- If present, version must be v2 or v3
subjectUniqueID [2] IMPLICIT UniqueIdentifier OPTIONAL,
-- If present, version must be v2 or v3
extensions [3] EXPLICIT Extensions OPTIONAL
-- If present, version must be v3
}
```
Certificates are instantiated using a certificate factory. The following is an example of how to instantiate an X.509 certificate:
```
try (InputStream inStream = new FileInputStream("fileName-of-cert")) {
CertificateFactory cf = CertificateFactory.getInstance("X.509");
X509Certificate cert = (X509Certificate)cf.generateCertificate(inStream);
}
```
**See also:**
- [Certificate](https://developer.android.com/reference/java/security/cert/Certificate)
- [CertificateFactory](https://developer.android.com/reference/java/security/cert/CertificateFactory)
- [X509Extension](https://developer.android.com/reference/java/security/cert/X509Extension)
## Summary
| ### Protected constructors ||
|-------------------------------------------------------------------------------------------------------------------------------------------------------------|---|
| ` `[X509Certificate](https://developer.android.com/reference/java/security/cert/X509Certificate#X509Certificate())`() ` Constructor for X.509 certificates. |
| ### Public methods ||
|------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| ` abstract void` | ` `[checkValidity](https://developer.android.com/reference/java/security/cert/X509Certificate#checkValidity())`() ` Checks that the certificate is currently valid. |
| ` abstract void` | ` `[checkValidity](https://developer.android.com/reference/java/security/cert/X509Certificate#checkValidity(java.util.Date))`(`[Date](https://developer.android.com/reference/java/util/Date)` date) ` Checks that the given date is within the certificate's validity period. |
| ` abstract int` | ` `[getBasicConstraints](https://developer.android.com/reference/java/security/cert/X509Certificate#getBasicConstraints())`() ` Gets the certificate constraints path length from the critical`BasicConstraints`extension, (OID = 2.5.29.19). |
| ` `[List](https://developer.android.com/reference/java/util/List)`<`[String](https://developer.android.com/reference/java/lang/String)`>` | ` `[getExtendedKeyUsage](https://developer.android.com/reference/java/security/cert/X509Certificate#getExtendedKeyUsage())`() ` Gets an unmodifiable list of Strings representing the OBJECT IDENTIFIERs of the`ExtKeyUsageSyntax`field of the extended key usage extension, (OID = 2.5.29.37). |
| ` `[Collection](https://developer.android.com/reference/java/util/Collection)`<`[List](https://developer.android.com/reference/java/util/List)`>` | ` `[getIssuerAlternativeNames](https://developer.android.com/reference/java/security/cert/X509Certificate#getIssuerAlternativeNames())`() ` Gets an immutable collection of issuer alternative names from the`IssuerAltName`extension, (OID = 2.5.29.18). |
| ` abstract `[Principal](https://developer.android.com/reference/java/security/Principal) | ` `[getIssuerDN](https://developer.android.com/reference/java/security/cert/X509Certificate#getIssuerDN())`() ` **Denigrated** , replaced by[getIssuerX500Principal()](https://developer.android.com/reference/java/security/cert/X509Certificate#getIssuerX500Principal()). |
| ` abstract boolean[]` | ` `[getIssuerUniqueID](https://developer.android.com/reference/java/security/cert/X509Certificate#getIssuerUniqueID())`() ` Gets the`issuerUniqueID`value from the certificate. |
| ` `[X500Principal](https://developer.android.com/reference/javax/security/auth/x500/X500Principal) | ` `[getIssuerX500Principal](https://developer.android.com/reference/java/security/cert/X509Certificate#getIssuerX500Principal())`() ` Returns the issuer (issuer distinguished name) value from the certificate as an`X500Principal`. |
| ` abstract boolean[]` | ` `[getKeyUsage](https://developer.android.com/reference/java/security/cert/X509Certificate#getKeyUsage())`() ` Gets a boolean array representing bits of the`KeyUsage`extension, (OID = 2.5.29.15). |
| ` abstract `[Date](https://developer.android.com/reference/java/util/Date) | ` `[getNotAfter](https://developer.android.com/reference/java/security/cert/X509Certificate#getNotAfter())`() ` Gets the`notAfter`date from the validity period of the certificate. |
| ` abstract `[Date](https://developer.android.com/reference/java/util/Date) | ` `[getNotBefore](https://developer.android.com/reference/java/security/cert/X509Certificate#getNotBefore())`() ` Gets the`notBefore`date from the validity period of the certificate. |
| ` abstract `[BigInteger](https://developer.android.com/reference/java/math/BigInteger) | ` `[getSerialNumber](https://developer.android.com/reference/java/security/cert/X509Certificate#getSerialNumber())`() ` Gets the`serialNumber`value from the certificate. |
| ` abstract `[String](https://developer.android.com/reference/java/lang/String) | ` `[getSigAlgName](https://developer.android.com/reference/java/security/cert/X509Certificate#getSigAlgName())`() ` Gets the signature algorithm name for the certificate signature algorithm. |
| ` abstract `[String](https://developer.android.com/reference/java/lang/String) | ` `[getSigAlgOID](https://developer.android.com/reference/java/security/cert/X509Certificate#getSigAlgOID())`() ` Gets the signature algorithm OID string from the certificate. |
| ` abstract byte[]` | ` `[getSigAlgParams](https://developer.android.com/reference/java/security/cert/X509Certificate#getSigAlgParams())`() ` Gets the DER-encoded signature algorithm parameters from this certificate's signature algorithm. |
| ` abstract byte[]` | ` `[getSignature](https://developer.android.com/reference/java/security/cert/X509Certificate#getSignature())`() ` Gets the`signature`value (the raw signature bits) from the certificate. |
| ` `[Collection](https://developer.android.com/reference/java/util/Collection)`<`[List](https://developer.android.com/reference/java/util/List)`>` | ` `[getSubjectAlternativeNames](https://developer.android.com/reference/java/security/cert/X509Certificate#getSubjectAlternativeNames())`() ` Gets an immutable collection of subject alternative names from the`SubjectAltName`extension, (OID = 2.5.29.17). |
| ` abstract `[Principal](https://developer.android.com/reference/java/security/Principal) | ` `[getSubjectDN](https://developer.android.com/reference/java/security/cert/X509Certificate#getSubjectDN())`() ` **Denigrated** , replaced by[getSubjectX500Principal()](https://developer.android.com/reference/java/security/cert/X509Certificate#getSubjectX500Principal()). |
| ` abstract boolean[]` | ` `[getSubjectUniqueID](https://developer.android.com/reference/java/security/cert/X509Certificate#getSubjectUniqueID())`() ` Gets the`subjectUniqueID`value from the certificate. |
| ` `[X500Principal](https://developer.android.com/reference/javax/security/auth/x500/X500Principal) | ` `[getSubjectX500Principal](https://developer.android.com/reference/java/security/cert/X509Certificate#getSubjectX500Principal())`() ` Returns the subject (subject distinguished name) value from the certificate as an`X500Principal`. |
| ` abstract byte[]` | ` `[getTBSCertificate](https://developer.android.com/reference/java/security/cert/X509Certificate#getTBSCertificate())`() ` Gets the DER-encoded certificate information, the`tbsCertificate`from this certificate. |
| ` abstract int` | ` `[getVersion](https://developer.android.com/reference/java/security/cert/X509Certificate#getVersion())`() ` Gets the`version`(version number) value from the certificate. |
| ` void` | ` `[verify](https://developer.android.com/reference/java/security/cert/X509Certificate#verify(java.security.PublicKey,%20java.security.Provider))`(`[PublicKey](https://developer.android.com/reference/java/security/PublicKey)` key, `[Provider](https://developer.android.com/reference/java/security/Provider)` sigProvider) ` Verifies that this certificate was signed using the private key that corresponds to the specified public key. |
| ### Inherited methods |
|-----------------------|---|
| From class` `[java.security.cert.Certificate](https://developer.android.com/reference/java/security/cert/Certificate)` ` |------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | ` boolean` | ` `[equals](https://developer.android.com/reference/java/security/cert/Certificate#equals(java.lang.Object))`(`[Object](https://developer.android.com/reference/java/lang/Object)` other) ` Compares this certificate for equality with the specified object. | | ` abstract byte[]` | ` `[getEncoded](https://developer.android.com/reference/java/security/cert/Certificate#getEncoded())`() ` Returns the encoded form of this certificate. | | ` abstract `[PublicKey](https://developer.android.com/reference/java/security/PublicKey) | ` `[getPublicKey](https://developer.android.com/reference/java/security/cert/Certificate#getPublicKey())`() ` Gets the public key from this certificate. | | ` final `[String](https://developer.android.com/reference/java/lang/String) | ` `[getType](https://developer.android.com/reference/java/security/cert/Certificate#getType())`() ` Returns the type of this certificate. | | ` int` | ` `[hashCode](https://developer.android.com/reference/java/security/cert/Certificate#hashCode())`() ` Returns a hashcode value for this certificate from its encoded form. | | ` abstract `[String](https://developer.android.com/reference/java/lang/String) | ` `[toString](https://developer.android.com/reference/java/security/cert/Certificate#toString())`() ` Returns a string representation of this certificate. | | ` abstract void` | ` `[verify](https://developer.android.com/reference/java/security/cert/Certificate#verify(java.security.PublicKey,%20java.lang.String))`(`[PublicKey](https://developer.android.com/reference/java/security/PublicKey)` key, `[String](https://developer.android.com/reference/java/lang/String)` sigProvider) ` Verifies that this certificate was signed using the private key that corresponds to the specified public key. | | ` void` | ` `[verify](https://developer.android.com/reference/java/security/cert/Certificate#verify(java.security.PublicKey,%20java.security.Provider))`(`[PublicKey](https://developer.android.com/reference/java/security/PublicKey)` key, `[Provider](https://developer.android.com/reference/java/security/Provider)` sigProvider) ` Verifies that this certificate was signed using the private key that corresponds to the specified public key. | | ` abstract void` | ` `[verify](https://developer.android.com/reference/java/security/cert/Certificate#verify(java.security.PublicKey))`(`[PublicKey](https://developer.android.com/reference/java/security/PublicKey)` key) ` Verifies that this certificate was signed using the private key that corresponds to the specified public key. | | ` `[Object](https://developer.android.com/reference/java/lang/Object) | ` `[writeReplace](https://developer.android.com/reference/java/security/cert/Certificate#writeReplace())`() ` Replace the Certificate to be serialized. | ||
| From class` `[java.lang.Object](https://developer.android.com/reference/java/lang/Object)` ` |--------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | ` `[Object](https://developer.android.com/reference/java/lang/Object) | ` `[clone](https://developer.android.com/reference/java/lang/Object#clone())`() ` Creates and returns a copy of this object. | | ` boolean` | ` `[equals](https://developer.android.com/reference/java/lang/Object#equals(java.lang.Object))`(`[Object](https://developer.android.com/reference/java/lang/Object)` obj) ` Indicates whether some other object is "equal to" this one. | | ` void` | ` `[finalize](https://developer.android.com/reference/java/lang/Object#finalize())`() ` Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. | | ` final `[Class](https://developer.android.com/reference/java/lang/Class)`` | ` `[getClass](https://developer.android.com/reference/java/lang/Object#getClass())`() ` Returns the runtime class of this`Object`. | | ` int` | ` `[hashCode](https://developer.android.com/reference/java/lang/Object#hashCode())`() ` Returns a hash code value for the object. | | ` final void` | ` `[notify](https://developer.android.com/reference/java/lang/Object#notify())`() ` Wakes up a single thread that is waiting on this object's monitor. | | ` final void` | ` `[notifyAll](https://developer.android.com/reference/java/lang/Object#notifyAll())`() ` Wakes up all threads that are waiting on this object's monitor. | | ` `[String](https://developer.android.com/reference/java/lang/String) | ` `[toString](https://developer.android.com/reference/java/lang/Object#toString())`() ` Returns a string representation of the object. | | ` final void` | ` `[wait](https://developer.android.com/reference/java/lang/Object#wait(long,%20int))`(long timeoutMillis, int nanos) ` Causes the current thread to wait until it is awakened, typically by being*notified* or*interrupted*, or until a certain amount of real time has elapsed. | | ` final void` | ` `[wait](https://developer.android.com/reference/java/lang/Object#wait(long))`(long timeoutMillis) ` Causes the current thread to wait until it is awakened, typically by being*notified* or*interrupted*, or until a certain amount of real time has elapsed. | | ` final void` | ` `[wait](https://developer.android.com/reference/java/lang/Object#wait())`() ` Causes the current thread to wait until it is awakened, typically by being*notified* or*interrupted*. | ||
| From interface` `[java.security.cert.X509Extension](https://developer.android.com/reference/java/security/cert/X509Extension)` ` |--------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | ` abstract `[Set](https://developer.android.com/reference/java/util/Set)`<`[String](https://developer.android.com/reference/java/lang/String)`>` | ` `[getCriticalExtensionOIDs](https://developer.android.com/reference/java/security/cert/X509Extension#getCriticalExtensionOIDs())`() ` Gets a Set of the OID strings for the extension(s) marked CRITICAL in the certificate/CRL managed by the object implementing this interface. | | ` abstract byte[]` | ` `[getExtensionValue](https://developer.android.com/reference/java/security/cert/X509Extension#getExtensionValue(java.lang.String))`(`[String](https://developer.android.com/reference/java/lang/String)` oid) ` Gets the DER-encoded OCTET string for the extension value (*extnValue* ) identified by the passed-in`oid`String. | | ` abstract `[Set](https://developer.android.com/reference/java/util/Set)`<`[String](https://developer.android.com/reference/java/lang/String)`>` | ` `[getNonCriticalExtensionOIDs](https://developer.android.com/reference/java/security/cert/X509Extension#getNonCriticalExtensionOIDs())`() ` Gets a Set of the OID strings for the extension(s) marked NON-CRITICAL in the certificate/CRL managed by the object implementing this interface. | | ` abstract boolean` | ` `[hasUnsupportedCriticalExtension](https://developer.android.com/reference/java/security/cert/X509Extension#hasUnsupportedCriticalExtension())`() ` Check if there is a critical extension that is not supported. | ||
## Protected constructors
### X509Certificate
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
protected X509Certificate ()
```
Constructor for X.509 certificates.
## Public methods
### checkValidity
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public abstract void checkValidity ()
```
Checks that the certificate is currently valid. It is if the current date and time are within the validity period given in the certificate.
The validity period consists of two date/time values: the first and last dates (and times) on which the certificate is valid. It is defined in ASN.1 as:
```
validity Validity
Validity ::= SEQUENCE {
notBefore CertificateValidityDate,
notAfter CertificateValidityDate }
CertificateValidityDate ::= CHOICE {
utcTime UTCTime,
generalTime GeneralizedTime }
```
| Throws ||
|-------------------------------------------------------------------------------------------------------------------------------|--------------------------------------|
| [CertificateExpiredException](https://developer.android.com/reference/java/security/cert/CertificateExpiredException) | if the certificate has expired. |
| [CertificateNotYetValidException](https://developer.android.com/reference/java/security/cert/CertificateNotYetValidException) | if the certificate is not yet valid. |
### checkValidity
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public abstract void checkValidity (Date date)
```
Checks that the given date is within the certificate's validity period. In other words, this determines whether the certificate would be valid at the given date/time.
| Parameters ||
|--------|-------------------------------------------------------------------------------------------------|
| `date` | `Date`: the Date to check against to see if this certificate is valid at that date/time.
|
| Throws ||
|-------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------|
| [CertificateExpiredException](https://developer.android.com/reference/java/security/cert/CertificateExpiredException) | if the certificate has expired with respect to the`date`supplied. |
| [CertificateNotYetValidException](https://developer.android.com/reference/java/security/cert/CertificateNotYetValidException) | if the certificate is not yet valid with respect to the`date`supplied. |
**See also:**
- [checkValidity()](https://developer.android.com/reference/java/security/cert/X509Certificate#checkValidity())
### getBasicConstraints
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public abstract int getBasicConstraints ()
```
Gets the certificate constraints path length from the critical`BasicConstraints`extension, (OID = 2.5.29.19).
The basic constraints extension identifies whether the subject of the certificate is a Certificate Authority (CA) and how deep a certification path may exist through that CA. The`pathLenConstraint`field (see below) is meaningful only if`cA`is set to TRUE. In this case, it gives the maximum number of CA certificates that may follow this certificate in a certification path. A value of zero indicates that only an end-entity certificate may follow in the path.
The ASN.1 definition for this is:
```
BasicConstraints ::= SEQUENCE {
cA BOOLEAN DEFAULT FALSE,
pathLenConstraint INTEGER (0..MAX) OPTIONAL }
```
| Returns ||
|-------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `int` | the value of`pathLenConstraint`if the BasicConstraints extension is present in the certificate and the subject of the certificate is a CA, otherwise -1. If the subject of the certificate is a CA and`pathLenConstraint`does not appear,`Integer.MAX_VALUE`is returned to indicate that there is no limit to the allowed length of the certification path.
|
### getExtendedKeyUsage
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public List getExtendedKeyUsage ()
```
Gets an unmodifiable list of Strings representing the OBJECT IDENTIFIERs of the`ExtKeyUsageSyntax`field of the extended key usage extension, (OID = 2.5.29.37). It indicates one or more purposes for which the certified public key may be used, in addition to or in place of the basic purposes indicated in the key usage extension field. The ASN.1 definition for this is:
```
ExtKeyUsageSyntax ::= SEQUENCE SIZE (1..MAX) OF KeyPurposeId
KeyPurposeId ::= OBJECT IDENTIFIER
```
Key purposes may be defined by any organization with a need. Object identifiers used to identify key purposes shall be assigned in accordance with IANA or ITU-T Rec. X.660 \| ISO/IEC/ITU 9834-1.
This method was added to version 1.4 of the Java 2 Platform Standard Edition. In order to maintain backwards compatibility with existing service providers, this method is not`abstract`and it provides a default implementation. Subclasses should override this method with a correct implementation.
| Returns ||
|----------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| [List](https://developer.android.com/reference/java/util/List)`<`[String](https://developer.android.com/reference/java/lang/String)`>` | the ExtendedKeyUsage extension of this certificate, as an unmodifiable list of object identifiers represented as Strings. Returns null if this certificate does not contain an ExtendedKeyUsage extension.
|
| Throws ||
|-----------------------------------------------------------------------------------------------------------------------|------------------------------------|
| [CertificateParsingException](https://developer.android.com/reference/java/security/cert/CertificateParsingException) | if the extension cannot be decoded |
### getIssuerAlternativeNames
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public Collection> getIssuerAlternativeNames ()
```
Gets an immutable collection of issuer alternative names from the`IssuerAltName`extension, (OID = 2.5.29.18).
The ASN.1 definition of the`IssuerAltName`extension is:
```
IssuerAltName ::= GeneralNames
```
The ASN.1 definition of`GeneralNames`is defined in[getSubjectAlternativeNames](https://developer.android.com/reference/java/security/cert/X509Certificate#getSubjectAlternativeNames()).
If this certificate does not contain an`IssuerAltName`extension,`null`is returned. Otherwise, a`Collection`is returned with an entry representing each`GeneralName`included in the extension. Each entry is a`List`whose first entry is an`Integer`(the name type, 0-8) and whose second entry is a`String`or a byte array (the name, in string or ASN.1 DER encoded form, respectively). For more details about the formats used for each name type, see the`getSubjectAlternativeNames`method.
Note that the`Collection`returned may contain more than one name of the same type. Also, note that the returned`Collection`is immutable and any entries containing byte arrays are cloned to protect against subsequent modifications.
This method was added to version 1.4 of the Java 2 Platform Standard Edition. In order to maintain backwards compatibility with existing service providers, this method is not`abstract`and it provides a default implementation. Subclasses should override this method with a correct implementation.
| Returns ||
|---------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------|
| [Collection](https://developer.android.com/reference/java/util/Collection)`<`[List](https://developer.android.com/reference/java/util/List)`>` | an immutable`Collection`of issuer alternative names (or`null`)
|
| Throws ||
|-----------------------------------------------------------------------------------------------------------------------|------------------------------------|
| [CertificateParsingException](https://developer.android.com/reference/java/security/cert/CertificateParsingException) | if the extension cannot be decoded |
### getIssuerDN
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public abstract Principal getIssuerDN ()
```
**Denigrated** , replaced by[getIssuerX500Principal()](https://developer.android.com/reference/java/security/cert/X509Certificate#getIssuerX500Principal()). This method returns the`issuer`as an implementation specific Principal object, which should not be relied upon by portable code.
Gets the`issuer`(issuer distinguished name) value from the certificate. The issuer name identifies the entity that signed (and issued) the certificate.
The issuer name field contains an X.500 distinguished name (DN). The ASN.1 definition for this is:
```
issuer Name
Name ::= CHOICE { RDNSequence }
RDNSequence ::= SEQUENCE OF RelativeDistinguishedName
RelativeDistinguishedName ::=
SET OF AttributeValueAssertion
AttributeValueAssertion ::= SEQUENCE {
AttributeType,
AttributeValue }
AttributeType ::= OBJECT IDENTIFIER
AttributeValue ::= ANY
```
The`Name`describes a hierarchical name composed of attributes, such as country name, and corresponding values, such as US. The type of the`AttributeValue`component is determined by the`AttributeType`; in general it will be a`directoryString`. A`directoryString`is usually one of`PrintableString`,`TeletexString`or`UniversalString`.
| Returns ||
|------------------------------------------------------------------------------|-----------------------------------------------------------------|
| [Principal](https://developer.android.com/reference/java/security/Principal) | a Principal whose name is the issuer distinguished name.
|
### getIssuerUniqueID
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public abstract boolean[] getIssuerUniqueID ()
```
Gets the`issuerUniqueID`value from the certificate. The issuer unique identifier is present in the certificate to handle the possibility of reuse of issuer names over time. RFC 3280 recommends that names not be reused and that conforming certificates not make use of unique identifiers. Applications conforming to that profile should be capable of parsing unique identifiers and making comparisons.
The ASN.1 definition for this is:
```
issuerUniqueID [1] IMPLICIT UniqueIdentifier OPTIONAL
UniqueIdentifier ::= BIT STRING
```
| Returns ||
|-------------|--------------------------------------------------------------------------------------|
| `boolean[]` | the issuer unique identifier or null if it is not present in the certificate.
|
### getIssuerX500Principal
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public X500Principal getIssuerX500Principal ()
```
Returns the issuer (issuer distinguished name) value from the certificate as an`X500Principal`.
It is recommended that subclasses override this method.
| Returns ||
|-------------------------------------------------------------------------------------------------|--------------------------------------------------------------------|
| [X500Principal](https://developer.android.com/reference/javax/security/auth/x500/X500Principal) | an`X500Principal`representing the issuer distinguished name
|
### getKeyUsage
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public abstract boolean[] getKeyUsage ()
```
Gets a boolean array representing bits of the`KeyUsage`extension, (OID = 2.5.29.15). The key usage extension defines the purpose (e.g., encipherment, signature, certificate signing) of the key contained in the certificate. The ASN.1 definition for this is:
```
KeyUsage ::= BIT STRING {
digitalSignature (0),
nonRepudiation (1),
keyEncipherment (2),
dataEncipherment (3),
keyAgreement (4),
keyCertSign (5),
cRLSign (6),
encipherOnly (7),
decipherOnly (8) }
```
RFC 3280 recommends that when used, this be marked as a critical extension.
| Returns ||
|-------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `boolean[]` | the KeyUsage extension of this certificate, represented as an array of booleans. The order of KeyUsage values in the array is the same as in the above ASN.1 definition. The array will contain a value for each KeyUsage defined above. If the KeyUsage list encoded in the certificate is longer than the above list, it will not be truncated. Returns null if this certificate does not contain a KeyUsage extension.
|
### getNotAfter
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public abstract Date getNotAfter ()
```
Gets the`notAfter`date from the validity period of the certificate. See[getNotBefore](https://developer.android.com/reference/java/security/cert/X509Certificate#getNotBefore())for relevant ASN.1 definitions.
| Returns ||
|----------------------------------------------------------------|---------------------------------------------|
| [Date](https://developer.android.com/reference/java/util/Date) | the end date of the validity period.
|
**See also:**
- [checkValidity()](https://developer.android.com/reference/java/security/cert/X509Certificate#checkValidity())
### getNotBefore
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public abstract Date getNotBefore ()
```
Gets the`notBefore`date from the validity period of the certificate. The relevant ASN.1 definitions are:
```
validity Validity
Validity ::= SEQUENCE {
notBefore CertificateValidityDate,
notAfter CertificateValidityDate }
CertificateValidityDate ::= CHOICE {
utcTime UTCTime,
generalTime GeneralizedTime }
```
| Returns ||
|----------------------------------------------------------------|-----------------------------------------------|
| [Date](https://developer.android.com/reference/java/util/Date) | the start date of the validity period.
|
**See also:**
- [checkValidity()](https://developer.android.com/reference/java/security/cert/X509Certificate#checkValidity())
### getSerialNumber
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public abstract BigInteger getSerialNumber ()
```
Gets the`serialNumber`value from the certificate. The serial number is an integer assigned by the certification authority to each certificate. It must be unique for each certificate issued by a given CA (i.e., the issuer name and serial number identify a unique certificate). The ASN.1 definition for this is:
```
serialNumber CertificateSerialNumber
CertificateSerialNumber ::= INTEGER
```
| Returns ||
|----------------------------------------------------------------------------|---------------------------|
| [BigInteger](https://developer.android.com/reference/java/math/BigInteger) | the serial number.
|
### getSigAlgName
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public abstract String getSigAlgName ()
```
Gets the signature algorithm name for the certificate signature algorithm. An example is the string "SHA256withRSA". The ASN.1 definition for this is:
```
signatureAlgorithm AlgorithmIdentifier
AlgorithmIdentifier ::= SEQUENCE {
algorithm OBJECT IDENTIFIER,
parameters ANY DEFINED BY algorithm OPTIONAL }
-- contains a value of the type
-- registered for use with the
-- algorithm object identifier value
```
The algorithm name is determined from the`algorithm`OID string.
| Returns ||
|--------------------------------------------------------------------|--------------------------------------|
| [String](https://developer.android.com/reference/java/lang/String) | the signature algorithm name.
|
### getSigAlgOID
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public abstract String getSigAlgOID ()
```
Gets the signature algorithm OID string from the certificate. An OID is represented by a set of nonnegative whole numbers separated by periods. For example, the string "1.2.840.10040.4.3" identifies the SHA-1 with DSA signature algorithm defined in[RFC 3279: Algorithms and Identifiers for the Internet X.509 Public Key Infrastructure Certificate and CRL Profile](http://www.ietf.org/rfc/rfc3279.txt).
See[getSigAlgName](https://developer.android.com/reference/java/security/cert/X509Certificate#getSigAlgName())for relevant ASN.1 definitions.
| Returns ||
|--------------------------------------------------------------------|--------------------------------------------|
| [String](https://developer.android.com/reference/java/lang/String) | the signature algorithm OID string.
|
### getSigAlgParams
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public abstract byte[] getSigAlgParams ()
```
Gets the DER-encoded signature algorithm parameters from this certificate's signature algorithm. In most cases, the signature algorithm parameters are null; the parameters are usually supplied with the certificate's public key. If access to individual parameter values is needed then use[AlgorithmParameters](https://developer.android.com/reference/java/security/AlgorithmParameters)and instantiate with the name returned by[getSigAlgName](https://developer.android.com/reference/java/security/cert/X509Certificate#getSigAlgName()).
See[getSigAlgName](https://developer.android.com/reference/java/security/cert/X509Certificate#getSigAlgName())for relevant ASN.1 definitions.
| Returns ||
|----------|----------------------------------------------------------------------------------------------|
| `byte[]` | the DER-encoded signature algorithm parameters, or null if no parameters are present.
|
### getSignature
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public abstract byte[] getSignature ()
```
Gets the`signature`value (the raw signature bits) from the certificate. The ASN.1 definition for this is:
```
signature BIT STRING
```
| Returns ||
|----------|-----------------------|
| `byte[]` | the signature.
|
### getSubjectAlternativeNames
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public Collection> getSubjectAlternativeNames ()
```
Gets an immutable collection of subject alternative names from the`SubjectAltName`extension, (OID = 2.5.29.17).
The ASN.1 definition of the`SubjectAltName`extension is:
```
SubjectAltName ::= GeneralNames
GeneralNames :: = SEQUENCE SIZE (1..MAX) OF GeneralName
GeneralName ::= CHOICE {
otherName [0] OtherName,
rfc822Name [1] IA5String,
dNSName [2] IA5String,
x400Address [3] ORAddress,
directoryName [4] Name,
ediPartyName [5] EDIPartyName,
uniformResourceIdentifier [6] IA5String,
iPAddress [7] OCTET STRING,
registeredID [8] OBJECT IDENTIFIER}
```
If this certificate does not contain a`SubjectAltName`extension,`null`is returned. Otherwise, a`Collection`is returned with an entry representing each`GeneralName`included in the extension. Each entry is a`List`whose first entry is an`Integer`(the name type, 0-8) and whose second entry is a`String`or a byte array (the name, in string or ASN.1 DER encoded form, respectively).
[RFC 822](http://www.ietf.org/rfc/rfc822.txt), DNS, and URI names are returned as`String`s, using the well-established string formats for those types (subject to the restrictions included in RFC 3280). IPv4 address names are returned using dotted quad notation. IPv6 address names are returned in the form "a1:a2:...:a8", where a1-a8 are hexadecimal values representing the eight 16-bit pieces of the address. OID names are returned as`String`s represented as a series of nonnegative integers separated by periods. And directory names (distinguished names) are returned in[RFC 2253](http://www.ietf.org/rfc/rfc2253.txt)string format. No standard string format is defined for otherNames, X.400 names, EDI party names, or any other type of names. They are returned as byte arrays containing the ASN.1 DER encoded form of the name.
Note that the`Collection`returned may contain more than one name of the same type. Also, note that the returned`Collection`is immutable and any entries containing byte arrays are cloned to protect against subsequent modifications.
This method was added to version 1.4 of the Java 2 Platform Standard Edition. In order to maintain backwards compatibility with existing service providers, this method is not`abstract`and it provides a default implementation. Subclasses should override this method with a correct implementation.
| Returns ||
|---------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------|
| [Collection](https://developer.android.com/reference/java/util/Collection)`<`[List](https://developer.android.com/reference/java/util/List)`>` | an immutable`Collection`of subject alternative names (or`null`)
|
| Throws ||
|-----------------------------------------------------------------------------------------------------------------------|------------------------------------|
| [CertificateParsingException](https://developer.android.com/reference/java/security/cert/CertificateParsingException) | if the extension cannot be decoded |
### getSubjectDN
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public abstract Principal getSubjectDN ()
```
**Denigrated** , replaced by[getSubjectX500Principal()](https://developer.android.com/reference/java/security/cert/X509Certificate#getSubjectX500Principal()). This method returns the`subject`as an implementation specific Principal object, which should not be relied upon by portable code.
Gets the`subject`(subject distinguished name) value from the certificate. If the`subject`value is empty, then the`getName()`method of the returned`Principal`object returns an empty string ("").
The ASN.1 definition for this is:
```
subject Name
```
See[getIssuerDN](https://developer.android.com/reference/java/security/cert/X509Certificate#getIssuerDN())for`Name`and other relevant definitions.
| Returns ||
|------------------------------------------------------------------------------|----------------------------------------------------|
| [Principal](https://developer.android.com/reference/java/security/Principal) | a Principal whose name is the subject name.
|
### getSubjectUniqueID
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public abstract boolean[] getSubjectUniqueID ()
```
Gets the`subjectUniqueID`value from the certificate.
The ASN.1 definition for this is:
```
subjectUniqueID [2] IMPLICIT UniqueIdentifier OPTIONAL
UniqueIdentifier ::= BIT STRING
```
| Returns ||
|-------------|---------------------------------------------------------------------------------------|
| `boolean[]` | the subject unique identifier or null if it is not present in the certificate.
|
### getSubjectX500Principal
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public X500Principal getSubjectX500Principal ()
```
Returns the subject (subject distinguished name) value from the certificate as an`X500Principal`. If the subject value is empty, then the`getName()`method of the returned`X500Principal`object returns an empty string ("").
It is recommended that subclasses override this method.
| Returns ||
|-------------------------------------------------------------------------------------------------|---------------------------------------------------------------------|
| [X500Principal](https://developer.android.com/reference/javax/security/auth/x500/X500Principal) | an`X500Principal`representing the subject distinguished name
|
### getTBSCertificate
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public abstract byte[] getTBSCertificate ()
```
Gets the DER-encoded certificate information, the`tbsCertificate`from this certificate. This can be used to verify the signature independently.
| Returns ||
|----------|-------------------------------------------------|
| `byte[]` | the DER-encoded certificate information.
|
| Throws ||
|-------------------------------------------------------------------------------------------------------------------------|------------------------------|
| [CertificateEncodingException](https://developer.android.com/reference/java/security/cert/CertificateEncodingException) | if an encoding error occurs. |
### getVersion
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public abstract int getVersion ()
```
Gets the`version`(version number) value from the certificate. The ASN.1 definition for this is:
```
version [0] EXPLICIT Version DEFAULT v1
Version ::= INTEGER { v1(0), v2(1), v3(2) }
```
| Returns ||
|-------|--------------------------------------------|
| `int` | the version number, i.e. 1, 2 or 3.
|
### verify
Added in[API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public void verify (PublicKey key,
Provider sigProvider)
```
Verifies that this certificate was signed using the private key that corresponds to the specified public key. This method uses the signature verification engine supplied by the specified provider. Note that the specified Provider object does not have to be registered in the provider list. This method was added to version 1.8 of the Java Platform Standard Edition. In order to maintain backwards compatibility with existing service providers, this method is not`abstract`and it provides a default implementation.
| Parameters ||
|---------------|-----------------------------------------------------------------------|
| `key` | `PublicKey`: the PublicKey used to carry out the verification.
|
| `sigProvider` | `Provider`: the signature provider.
|
| Throws ||
|------------------------------------------------------------------------------------------------------------------|--------------------------------------|
| [NoSuchAlgorithmException](https://developer.android.com/reference/java/security/NoSuchAlgorithmException) | on unsupported signature algorithms. |
| [InvalidKeyException](https://developer.android.com/reference/java/security/InvalidKeyException) | on incorrect key. |
| [SignatureException](https://developer.android.com/reference/java/security/SignatureException) | on signature errors. |
| [CertificateException](https://developer.android.com/reference/java/security/cert/CertificateException) | on encoding errors. |
| [UnsupportedOperationException](https://developer.android.com/reference/java/lang/UnsupportedOperationException) | if the method is not supported |