javax.crypto.Cipher — clojure-interop/javax.crypto 1.0.2

This class provides the functionality of a cryptographic cipher for encryption and decryption. It forms the core of the Java Cryptographic Extension (JCE) framework.

In order to create a Cipher object, the application calls the Cipher's getInstance method, and passes the name of the requested transformation to it. Optionally, the name of a provider may be specified.

A transformation is a string that describes the operation (or set of operations) to be performed on the given input, to produce some output. A transformation always includes the name of a cryptographic algorithm (e.g., AES), and may be followed by a feedback mode and padding scheme.

A transformation is of the form:

algorithm/mode/padding or

algorithm

(in the latter case, provider-specific default values for the mode and padding scheme are used). For example, the following is a valid transformation:

Cipher c = Cipher.getInstance(`AES/CBC/PKCS5Padding`);

Using modes such as CFB and OFB, block ciphers can encrypt data in units smaller than the cipher's actual block size. When requesting such a mode, you may optionally specify the number of bits to be processed at a time by appending this number to the mode name as shown in the AES/CFB8/NoPadding and AES/OFB32/PKCS5Padding transformations. If no such number is specified, a provider-specific default is used. Thus, block ciphers can be turned into byte-oriented stream ciphers by using an 8 bit mode such as CFB8 or OFB8.

Modes such as Authenticated Encryption with Associated Data (AEAD) provide authenticity assurances for both confidential data and Additional Associated Data (AAD) that is not encrypted. (Please see RFC 5116 for more information on AEAD and AEAD algorithms such as GCM/CCM.) Both confidential and AAD data can be used when calculating the authentication tag (similar to a Mac). This tag is appended to the ciphertext during encryption, and is verified on decryption.

AEAD modes such as GCM/CCM perform all AAD authenticity calculations before starting the ciphertext authenticity calculations. To avoid implementations having to internally buffer ciphertext, all AAD data must be supplied to GCM/CCM implementations (via the updateAAD methods) before the ciphertext is processed (via the update and doFinal methods).

Note that GCM mode has a uniqueness requirement on IVs used in encryption with a given key. When IVs are repeated for GCM encryption, such usages are subject to forgery attacks. Thus, after each encryption operation using GCM mode, callers should re-initialize the cipher objects with GCM parameters which has a different IV value.

GCMParameterSpec s = ...;
cipher.init(..., s);

// If the GCM parameters were generated by the provider, it can
// be retrieved by:
// cipher.getParameters().getParameterSpec(GCMParameterSpec.class);

cipher.updateAAD(...);  // AAD
cipher.update(...);     // Multi-part update
cipher.doFinal(...);    // conclusion of operation

// Use a different IV value for every encryption
byte[] newIv = ...;
s = new GCMParameterSpec(s.getTLen(), newIv);
cipher.init(..., s);
...

Every implementation of the Java platform is required to support the following standard Cipher transformations with the keysizes in parentheses:

AES/CBC/NoPadding (128) AES/CBC/PKCS5Padding (128) AES/ECB/NoPadding (128) AES/ECB/PKCS5Padding (128) DES/CBC/NoPadding (56) DES/CBC/PKCS5Padding (56) DES/ECB/NoPadding (56) DES/ECB/PKCS5Padding (56) DESede/CBC/NoPadding (168) DESede/CBC/PKCS5Padding (168) DESede/ECB/NoPadding (168) DESede/ECB/PKCS5Padding (168) RSA/ECB/PKCS1Padding (1024, 2048) RSA/ECB/OAEPWithSHA-1AndMGF1Padding (1024, 2048) RSA/ECB/OAEPWithSHA-256AndMGF1Padding (1024, 2048)

These transformations are described in the

Cipher section of the Java Cryptography Architecture Standard Algorithm Name Documentation. Consult the release documentation for your implementation to see if any other transformations are supported.

*-decrypt-mode clj

Static Constant.

Constant used to initialize cipher to decryption mode.

type: int

*-encrypt-mode clj

Static Constant.

Constant used to initialize cipher to encryption mode.

type: int

*-private-key clj

Static Constant.

Constant used to indicate the to-be-unwrapped key is a private key.

type: int

*-public-key clj

Static Constant.

Constant used to indicate the to-be-unwrapped key is a public key.

type: int

*-secret-key clj

Static Constant.

Constant used to indicate the to-be-unwrapped key is a secret key.

type: int

*-unwrap-mode clj

Static Constant.

Constant used to initialize cipher to key-unwrapping mode.

type: int

*-wrap-mode clj

Static Constant.

Constant used to initialize cipher to key-wrapping mode.

type: int

*get-instance clj

(*get-instance transformation)

(*get-instance transformation provider)

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() method.

transformation - the name of the transformation, e.g., AES/CBC/PKCS5Padding. See the Cipher section in the Java Cryptography Architecture Standard Algorithm Name Documentation for information about standard transformation names. - java.lang.String provider - the name of the provider. - java.lang.String

returns: a cipher that implements the requested transformation. - javax.crypto.Cipher

throws: java.security.NoSuchAlgorithmException - if transformation is null, empty, in an invalid format, or if a CipherSpi implementation for the specified algorithm is not available from the specified provider.

*get-max-allowed-key-length clj

(*get-max-allowed-key-length transformation)

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.

transformation - the cipher transformation. - java.lang.String

returns: the maximum key length in bits or Integer.MAX_VALUE. - int

throws: java.lang.NullPointerException - if transformation is null.

*get-max-allowed-parameter-spec clj

(*get-max-allowed-parameter-spec transformation)

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.

transformation - the cipher transformation. - java.lang.String

returns: an AlgorithmParameterSpec which holds the maximum value or null. - java.security.spec.AlgorithmParameterSpec

throws: java.lang.NullPointerException - if transformation is null.

do-final clj

(do-final this)

(do-final this input)

(do-final this output output-offset)

(do-final this input input-offset input-len)

(do-final this input input-offset input-len output)

(do-final this input input-offset input-len output output-offset)

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 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.

input - the input buffer - byte[] input-offset - the offset in input where the input starts - int input-len - the input length - int output - the buffer for the result - byte[] output-offset - the offset in output where the result is stored - int

returns: the number of bytes stored in output - int

throws: java.lang.IllegalStateException - if this cipher is in a wrong state (e.g., has not been initialized)

get-algorithm clj

(get-algorithm this)

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..

returns: the algorithm name of this Cipher object. - java.lang.String

get-block-size clj

(get-block-size this)

Returns the block size (in bytes).

returns: the block size (in bytes), or 0 if the underlying algorithm is not a block cipher - int

get-exemption-mechanism clj

(get-exemption-mechanism this)

Returns the exemption mechanism object used with this cipher.

returns: the exemption mechanism object used with this cipher, or null if this cipher does not use any exemption mechanism. - javax.crypto.ExemptionMechanism

get-iv clj

(get-iv this)

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.

returns: the initialization vector in a new buffer, or null if the underlying algorithm does not use an IV, or if the IV has not yet been set. - byte[]

get-output-size clj

(get-output-size this input-len)

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.

input-len - the input length (in bytes) - int

returns: the required output buffer size (in bytes) - int

throws: java.lang.IllegalStateException - if this cipher is in a wrong state (e.g., has not yet been initialized)

get-parameters clj

(get-parameters this)

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.

returns: the parameters used with this cipher, or null if this cipher does not use any parameters. - java.security.AlgorithmParameters

get-provider clj

(get-provider this)

Returns the provider of this Cipher object.

returns: the provider of this Cipher object - java.security.Provider

init clj

(init this opmode key)

(init this opmode key random)

(init this opmode key params random)

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 or 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.

opmode - the operation mode of this cipher (this is one of the following: ENCRYPT_MODE, DECRYPT_MODE, WRAP_MODE or UNWRAP_MODE) - int key - the encryption key - java.security.Key params - the algorithm parameters - java.security.spec.AlgorithmParameterSpec random - the source of randomness - java.security.SecureRandom

throws: java.security.InvalidKeyException - if the given key is inappropriate for initializing this cipher, or its keysize exceeds the maximum allowable keysize (as determined from the configured jurisdiction policy files).

unwrap clj

(unwrap this wrapped-key wrapped-key-algorithm wrapped-key-type)

Unwrap a previously wrapped key.

wrapped-key - the key to be unwrapped. - byte[] wrapped-key-algorithm - the algorithm associated with the wrapped key. - java.lang.String wrapped-key-type - the type of the wrapped key. This must be one of SECRET_KEY, PRIVATE_KEY, or PUBLIC_KEY. - int

returns: the unwrapped key. - java.security.Key

throws: java.lang.IllegalStateException - if this cipher is in a wrong state (e.g., has not been initialized).

update clj

(update this input)

(update this input output)

(update this input input-offset input-len)

(update this input input-offset input-len output)

(update this input input-offset input-len output output-offset)

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 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.

input - the input buffer - byte[] input-offset - the offset in input where the input starts - int input-len - the input length - int output - the buffer for the result - byte[] output-offset - the offset in output where the result is stored - int

returns: the number of bytes stored in output - int

throws: java.lang.IllegalStateException - if this cipher is in a wrong state (e.g., has not been initialized)

update-aad clj

(update-aad this src)

(update-aad this src offset len)

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).

src - the buffer containing the AAD - byte[] offset - the offset in src where the AAD input starts - int len - the number of AAD bytes - int

throws: java.lang.IllegalArgumentException - if the src byte array is null, or the offset or length is less than 0, or the sum of the offset and len is greater than the length of the src byte array

wrap clj

(wrap this key)

Wrap a key.

key - the key to be wrapped. - java.security.Key

returns: the wrapped key. - byte[]

throws: java.lang.IllegalStateException - if this cipher is in a wrong state (e.g., has not been initialized).