Class AEADCipher

java.lang.Object
javacardx.crypto.Cipher
javacardx.crypto.AEADCipher
public abstract class AEADCipher extends Cipher
The AEADCipher class is the abstract base class for Authenticated Encryption with Associated Data (AEAD) ciphers.

Examples of AEAD algorithms are the GCM and CCM modes of operation for AES.

AEAD ciphers can be created by the Cipher.getInstance method using the ALG_AES_GCM and ALG_AES_CCM algorithm constants. The returned Cipher instance should then be cast to AEADCipher.

A tear or card reset event resets an initialized AEADCipher object to a state where:

  • the key and the mode are the same as when previously initialized via a call to init().
  • Other initial values passed within init() methods e.g tagSize, messageLen, IV, nonce are reset to 0.

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. It is recommended to provide new initial values, not full of zeroes, with a new call to init().

Note: For algorithms which support keys with transient key data sets, e.g AES, the AEADCipher object key becomes uninitialized on clear events associated with the Key object used to initialize the AEADCipher object.

Since:
3.0.5

  • Field Details

  • Constructor Details

    • AEADCipher

      protected AEADCipher()
      Avoid instantiation, compatible with protected constructor of Cipher.

  • Method Details

    • init

      public abstract void init(Key theKey, byte theMode) throws CryptoException
      Initializes the AEADCipher object with the appropriate Key. This method should be used for algorithms which do not need initialization parameters or use default parameter values.

      init() must be used to update the AEADCipher object with a new key. If the Key object is modified after invoking the init() method, the behavior of the update() and doFinal() methods is unspecified.

      The Key is checked for consistency with the Cipher algorithm. For example, the key type must be matched. Additional key componentdomain parameter strength checks are implementation specific.

      Note:

      • AEADCipher in GCM mode will use a 12 bytes length buffer full of 0 for initial vector(IV) if this method is used.

      Specified by:
      init in class Cipher
      Parameters:
      theKey - the key object to use for encrypting or decrypting
      theMode - one of MODE_DECRYPT or MODE_ENCRYPT
      Throws:
      CryptoException - with the following reason codes:
      • CryptoException.ILLEGAL_VALUE if theMode option is an undefined value or if the Key is inconsistent with the AEADCipher implementation.
      • CryptoException.UNINITIALIZED_KEY if theKey instance is uninitialized.
      • CryptoException.INVALID_INIT if this method is called for an offline mode of encryption
      Since:
      3.0.5

    • init

      public abstract void init(Key theKey, byte theMode, byte[] bArray, short bOff, short bLen) throws CryptoException
      Initializes the AEADCipher object with the appropriate Key and algorithm specific parameters.

      init() must be used to update the AEADCipher object with a new key. If the Key object is modified after invoking the init() method, the behavior of the update() and doFinal() methods is unspecified.

      The Key is checked for consistency with the Cipher algorithm. For example, the key type must be matched. Additional key component parameter strength checks are implementation specific.

      Note:

      • AEADCipher in GCM mode will use barray for initial vector(IV) if this method is used.

      Specified by:
      init in class Cipher
      Parameters:
      theKey - the key object to use for encrypting or decrypting.
      theMode - one of MODE_DECRYPT or MODE_ENCRYPT
      bArray - byte array containing algorithm specific initialization info
      bOff - offset within bArray where the algorithm specific data begins
      bLen - byte length of algorithm specific parameter data
      Throws:
      CryptoException - with the following reason codes:
      • CryptoException.ILLEGAL_VALUE if theMode option is an undefined value or if a byte array parameter option is not supported by the algorithm or if the bLen is an incorrect byte length for the algorithm specific data or if the Key is inconsistent with the AEADCipher implementation.
      • CryptoException.UNINITIALIZED_KEY if theKey instance is uninitialized.
      • CryptoException.INVALID_INIT if this method is called for an offline mode of encryption
      Since:
      3.0.5

    • init

      public abstract void init(Key theKey, byte theMode, byte[] nonceBuf, short nonceOff, short nonceLen, short adataLen, short messageLen, short tagSize) throws CryptoException
      Initializes this AEADCipher instance to encrypt or decrypt with the given key, nonce, AAD size and message size.

      This method should only be called for offline cipher mode encryption such as ALG_AES_CCM. In offline cipher mode encryption the length of the authentication data, message size and authentication tag must be known in advance.

      Parameters:
      theKey - the key object to use for encrypting or decrypting
      theMode - one of MODE_DECRYPT or MODE_ENCRYPT
      nonceBuf - a buffer holding the nonce
      nonceOff - the offset in the buffer of the nonce
      nonceLen - the length in the buffer of the nonce
      adataLen - the length of the authenticated data as presented in the updateAAD method
      messageLen - the length of the message as presented in the update and doFinal methods
      tagSize - the size in in bytes of the authentication tag
      Throws:
      CryptoException - with the following reason codes:
      Since:
      3.0.5

    • updateAAD

      public abstract void updateAAD(byte[] aadBuf, short aadOff, short aadLen) throws CryptoException
      Continues a multi-part update of the Additional Associated Data (AAD) that will be verified by the authentication tag. The data is not included with the ciphertext by this method.
      Parameters:
      aadBuf - the buffer containing the AAD data
      aadOff - the offset of the AAD data in the buffer
      aadLen - the length in bytes of the AAD data in the buffer
      Throws:
      CryptoException - with the following reason codes:
      • ILLEGAL_USE if updating the AAD value is conflicting with the state of this cipher
      • ILLEGAL_VALUE for CCM if the total AAD size provided, in all calls to this method, exceeds the AAD size given in the initial block used as IV
      Since:
      3.0.5

    • update

      public abstract short update(byte[] inBuff, short inOffset, short inLength, byte[] outBuff, short outOffset) throws CryptoException
      Continues a multiple-part encryption or decryption operation, processing additional input data.

      This method requires temporary storage of intermediate results. In addition, if the input data length is not block aligned (multiple of block size) then additional internal storage may be allocated at this time to store a partial input data block. This may result in additional resource consumption and/or slow performance.

      This method should only be used if all the input data required for the cipher is not available in one byte array. If all the input data required for the cipher is located in a single byte array, use of the doFinal() method to process all of the input data is recommended. The doFinal() method must be invoked to complete processing of any remaining input data buffered by one or more calls to the update() method.

      This method must write as much output as can be generated from the input data received so far. The output data length depends on the algorithm, the padding and the mode.

      For operations based on stream cipher algorithms (ALG_AES_CCM, CIPHER_AES_CCM, ALG_AES_GCM and CIPHER_AES_GCM), update() must process all bytes from input buffer and write the corresponding result. In this case, n input bytes generate n bytes of output data.

      Notes:

      • When using block-aligned data (multiple of block size), if the input buffer, inBuff and the output buffer, outBuff refer to the same array, or if any of these arguments refer to an array view sharing components with the other argument, then the output data area must not partially overlap the input data area such that the input data is modified before it is used.
        Example: if         inBuff==outBuff and inOffset < outOffset < inOffset+inLength, incorrect output may result.
      • When non-block aligned data is presented as input data, no amount of input and output buffer data overlap is allowed.
        Example: if         inBuff==outBuff and outOffset < inOffset+inLength, incorrect output may result.
      • On encryption and decryption operations, block alignment considerations may require that the number of bytes output into outBuff be larger or smaller than inLength or even 0.
      • If inLength is 0 this method does nothing.

      In addition to returning a short result, this method sets the result in an internal state which can be rechecked using assertion methods of the SensitiveResult class, if supported by the platform.

      Specified by:
      update in class Cipher
      Parameters:
      inBuff - the input buffer of data to be encrypted/decrypted
      inOffset - the offset into the input buffer at which to begin encryption/decryption
      inLength - the byte length to be encrypted/decrypted
      outBuff - the output buffer, may be the same as the input buffer
      outOffset - the offset into the output buffer where the resulting ciphertext/plaintext begins
      Returns:
      number of bytes output in outBuff
      Throws:
      CryptoException - with the following reason codes:
      • INVALID_INIT if this AEADCipher object is not initialized.
      • CryptoException.UNINITIALIZED_KEY if key not initialized.
      • ILLEGAL_USE
        • for CCM if AAD is not provided while it is indicated in the initial block used as IV
        • for CCM if the payload exceeds the payload size given in the initial block used as IV
      Since:
      3.0.5

    • doFinal

      public abstract short doFinal(byte[] inBuff, short inOffset, short inLength, byte[] outBuff, short outOffset) throws CryptoException
      Generates encrypted/decrypted output from all/last input data. This method must be invoked to complete a cipher operation. This method processes any remaining input data buffered by one or more calls to the update() method as well as input data supplied in the inBuff parameter.

      A call to this method also resets this AEADCipher object to a state where:

      • the key and the mode are the same as when previously initialized via a call to init().
      • other initial values passed within init() methods e.g tagSize, messageLen, IV, nonce are reset to 0 except tagSize required for subsequent calls to retrieveTag and verifyTag.

      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. It is recommended to provide new initial values, not full of zeroes, with a new call to init().

      Notes:

      • When using block-aligned data (multiple of block size), if the input buffer, inBuff and the output buffer, outBuff refer to the same array, or if any of these arguments refer to an array view sharing components with the other argument, then the output data area must not partially overlap the input data area such that the input data is modified before it is used.
        Example: if         inBuff==outBuff and inOffset < outOffset < inOffset+inLength, incorrect output may result.
      • When non-block aligned data is presented as input data, no amount of input and output buffer data overlap is allowed.
        Example: if         inBuff==outBuff and outOffset < inOffset+inLength, incorrect output may result.
      • On encryption and decryption operations, the number of bytes output into outBuff may be larger or smaller than inLength or even 0.
      • On decryption operations resulting in an ArrayIndexOutOfBoundsException, outBuff may be partially modified.

      In addition to returning a short result, this method sets the result in an internal state which can be rechecked using assertion methods of the SensitiveResult class, if supported by the platform.

      Specified by:
      doFinal in class Cipher
      Parameters:
      inBuff - the input buffer of data to be encrypted/decrypted
      inOffset - the offset into the input buffer at which to begin encryption/decryption
      inLength - the byte length to be encrypted/decrypted
      outBuff - the output buffer, may be the same as the input buffer
      outOffset - the offset into the output buffer where the resulting output data begins
      Returns:
      number of bytes output in outBuff
      Throws:
      CryptoException - with the following reason codes:
      • INVALID_INIT if this AEADCipher object is not initialized.
      • UNINITIALIZED_KEY if key not initialized.
      • ILLEGAL_USE
        • for CCM if all Additional Authenticated Data (AAD) was not provided
        • for CCM if the total message size provided is not identical to the messageLen parameter given in the init method
      Since:
      3.0.5

    • retrieveTag

      public abstract short retrieveTag(byte[] tagBuf, short tagOff, short tagLen) throws CryptoException
      Retrieves tagLen bytes from the calculated authentication tag. Depending on the algorithm, only certain tag lengths may be supported.

      Note:

      In addition to returning a short result, this method sets the result in an internal state which can be rechecked using assertion methods of the SensitiveResult class, if supported by the platform.

      Parameters:
      tagBuf - the buffer that will contain the authentication tag
      tagOff - the offset of the authentication tag in the buffer
      tagLen - the length in bytes of the authentication tag in the buffer
      Returns:
      the tag length, as given by tagLen (for convenience)
      Throws:
      CryptoException - with the following reason codes
      Since:
      3.0.5

    • verifyTag

      public abstract boolean verifyTag(byte[] receivedTagBuf, short receivedTagOff, short receivedTagLen, short requiredTagLen) throws CryptoException
      Verifies the authentication tag using the number of bytes set in requiredTagLen bytes. Depending on the algorithm, only certain tag lengths may be supported. For all algorithms the tag length must be a multiple of 8 bits.

      Notes:

      • This method may only be called for MODE_DECRYPT after doFinal has been called.
      • If recievedTagLen and requiredTagLen are valid values and recievedTagLen < requiredTagLen, the method returns false.

      In addition to returning a boolean result, this method sets the result in an internal state which can be rechecked using assertion methods of the SensitiveResult class, if supported by the platform.

      Parameters:
      receivedTagBuf - the buffer that will contain the received authentication tag
      receivedTagOff - the offset of the received authentication tag in the buffer
      receivedTagLen - the length in bytes of the received authentication tag in the buffer
      requiredTagLen - the required length in bytes of the received authentication tag, usually a constant value
      Returns:
      true if successfully verified, false otherwise
      Throws:
      CryptoException - with the following reason codes:
      Since:
      3.0.5