Added in API level 37

AutofillNoiseInjectedData

class AutofillNoiseInjectedData : Parcelable
kotlin.Any
   ↳ android.view.autofill.AutofillNoiseInjectedData

Represents the noise-injected version of a text field's content, generated using a differential privacy algorithm. While the Autofill providers won't be able to recover the actual text from the noise-injected data from one device, with uploads from sufficient number of devices, the Autofill providers are able to rebuild the constant, non-private parts of the text to help them improve Autofill detection's quality.

The noise injection process involves the following steps: 1. The original string is converted to a byte array using UTF-8 Encoding. The actual length of the string is hidden by padding with 0x0000 or truncating as needed. 2. Then for each bit in the byte array, random noise is introduced by "coin flipping": first we flip a coin to decide whether to change this bit. The probability is 50%. If we decide to change this bit, then we flip another coin to decide its new value. The probability is: 50% to be 1, 50% to be 0. 3. To further enhance privacy, each device may drop some of the bits after noise injection. getRetainedBitMask() tells you which bits are retained for the current payload.

With the coin flipping mechanism described above, each bit has 75% chance to report the real value, and 25% chance to report the opposite value(e.g. real value is 1, reported value is 0). This means if a bit remains the same across all devices(i.e. it's a part of a non-personalized string such as "Country"), then with a large enough amount of reports collected from different devices, then the ratio of real value among all reports should be close to 75%. In another word, if we see close to 75% of the reports show 1 then the real value of this bit should be a constant 1; if we see close to 75% of the reports show 0 then the real value of this bit should be a constant 0; all other distributions indicate this bit is not same across different devices(hence very likely to be personalized/private information), which should be discarded as noise.

Summary

Inherited constants
Public methods
Int

Describe the kinds of special objects contained in this Parcelable instance's marshaled representation.
Boolean
equals(other: Any?)

Indicates whether some other object is "equal to" this one.
ByteArray

Gets the noise-injected and bit-reduced data.
Byte

Returns a bit mask indicating which bits were retained for *each byte* in the payload returned by getNoiseInjectedPayload().
Int

Returns a hash code value for the object.
Unit
writeToParcel(dest: Parcel, flags: Int)

Flatten this object in to a Parcel.
Properties
static Parcelable.Creator<AutofillNoiseInjectedData!>

Public methods

describeContents

Added in API level 37
fun describeContents(): Int

Describe the kinds of special objects contained in this Parcelable instance's marshaled representation. For example, if the object will include a file descriptor in the output of writeToParcel(Parcel,int), the return value of this method must include the CONTENTS_FILE_DESCRIPTOR bit.

Return
Int a bitmask indicating the set of special object types marshaled by this Parcelable object instance.
Value is either 0 or

equals

Added in API level 37
fun equals(other: Any?): Boolean

Indicates whether some other object is "equal to" this one.

The equals method implements an equivalence relation on non-null object references:

  • It is reflexive: for any non-null reference value x, x.equals(x) should return true.
  • It is symmetric: for any non-null reference values x and y, x.equals(y) should return true if and only if y.equals(x) returns true.
  • It is transitive: for any non-null reference values x, y, and z, if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true.
  • It is consistent: for any non-null reference values x and y, multiple invocations of x.equals(y) consistently return true or consistently return false, provided no information used in equals comparisons on the objects is modified.
  • For any non-null reference value x, x.equals(null) should return false.

An equivalence relation partitions the elements it operates on into equivalence classes; all the members of an equivalence class are equal to each other. Members of an equivalence class are substitutable for each other, at least for some purposes.

Parameters
obj the reference object with which to compare.
Return
Boolean true if this object is the same as the obj argument; false otherwise.

getNoiseInjectedPayload

Added in API level 37
fun getNoiseInjectedPayload(): ByteArray

Gets the noise-injected and bit-reduced data. The original text has been transformed by a differential privacy algorithm, including random bit flips and removing some of the bits in every byte(getRetainedBitMask() tells you which bits are retained).

Return
ByteArray A byte array representing the obfuscated text.
This value cannot be null.

getRetainedBitMask

Added in API level 37
fun getRetainedBitMask(): Byte

Returns a bit mask indicating which bits were retained for *each byte* in the payload returned by getNoiseInjectedPayload(). Bits not retained are marked as 0 in the returned payload. The same bit mask is applied to every byte in the payload.

Return
Byte A byte where each bit corresponds to a bit position in a byte. If the n-th bit (0 <= n <= 7) is set, it means the n-th bit of each byte in the payload is retained.

hashCode

Added in API level 37
fun hashCode(): Int

Returns a hash code value for the object. This method is supported for the benefit of hash tables such as those provided by java.util.HashMap.

The general contract of hashCode is:

  • Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer, provided no information used in equals comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application.
  • If two objects are equal according to the equals method, then calling the hashCode method on each of the two objects must produce the same integer result.
  • It is not required that if two objects are unequal according to the equals method, then calling the hashCode method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hash tables.
Return
Int a hash code value for this object.

writeToParcel

Added in API level 37
fun writeToParcel(
    dest: Parcel, 
    flags: Int
): Unit

Flatten this object in to a Parcel.

Parameters
dest Parcel: This value cannot be null.
flags Int: Additional flags about how the object should be written. May be 0 or PARCELABLE_WRITE_RETURN_VALUE.
Value is either 0 or a combination of the following:

Properties

CREATOR

Added in API level 37
static val CREATOR: Parcelable.Creator<AutofillNoiseInjectedData!>