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ccm.h File Reference
Data Structures | Functions

ccm.h File Reference

CCM combines Counter mode encryption with CBC-MAC authentication for 128-bit block ciphers. More...

Go to the source code of this file.

Data Structures

struct  mbedtls_ccm_context
 The CCM context-type definition. More...

Functions

void mbedtls_ccm_init (mbedtls_ccm_context *ctx)
 This function initializes the specified CCM context, to make references valid, and prepare the context for mbedtls_ccm_setkey() or mbedtls_ccm_free().
int mbedtls_ccm_setkey (mbedtls_ccm_context *ctx, mbedtls_cipher_id_t cipher, const unsigned char *key, unsigned int keybits)
 This function initializes the CCM context set in the ctx parameter and sets the encryption key.
void mbedtls_ccm_free (mbedtls_ccm_context *ctx)
 This function releases and clears the specified CCM context and underlying cipher sub-context.
int mbedtls_ccm_encrypt_and_tag (mbedtls_ccm_context *ctx, size_t length, const unsigned char *iv, size_t iv_len, const unsigned char *add, size_t add_len, const unsigned char *input, unsigned char *output, unsigned char *tag, size_t tag_len)
 This function encrypts a buffer using CCM.
int mbedtls_ccm_auth_decrypt (mbedtls_ccm_context *ctx, size_t length, const unsigned char *iv, size_t iv_len, const unsigned char *add, size_t add_len, const unsigned char *input, unsigned char *output, const unsigned char *tag, size_t tag_len)
 This function performs a CCM authenticated decryption of a buffer.
int mbedtls_ccm_self_test (int verbose)
 The CCM checkup routine.

Detailed Description

CCM combines Counter mode encryption with CBC-MAC authentication for 128-bit block ciphers.

Input to CCM includes the following elements:

  • Payload - data that is both authenticated and encrypted.
  • Associated data (Adata) - data that is authenticated but not encrypted, For example, a header.
  • Nonce - A unique value that is assigned to the payload and the associated data.

Definition in file ccm.h.

Function Documentation

int mbedtls_ccm_auth_decrypt ( mbedtls_ccm_context *  ctx,
size_t  length,
const unsigned char *  iv,
size_t  iv_len,
const unsigned char *  add,
size_t  add_len,
const unsigned char *  input,
unsigned char *  output,
const unsigned char *  tag,
size_t  tag_len 
)

This function performs a CCM authenticated decryption of a buffer.

Parameters:
ctxThe CCM context to use for decryption.
lengthThe length of the input data in Bytes.
ivInitialization vector.
iv_lenThe length of the IV in Bytes: 7, 8, 9, 10, 11, 12, or 13.
addThe additional data field.
add_lenThe length of additional data in Bytes. Must be less than 2^16 - 2^8.
inputThe buffer holding the input data.
outputThe buffer holding the output data. Must be at least length Bytes wide.
tagThe buffer holding the tag.
tag_lenThe length of the tag in Bytes. 4, 6, 8, 10, 12, 14 or 16.
Returns:
0 if successful and authenticated, or MBEDTLS_ERR_CCM_AUTH_FAILED if the tag does not match.

Definition at line 322 of file ccm.c.

int mbedtls_ccm_encrypt_and_tag ( mbedtls_ccm_context *  ctx,
size_t  length,
const unsigned char *  iv,
size_t  iv_len,
const unsigned char *  add,
size_t  add_len,
const unsigned char *  input,
unsigned char *  output,
unsigned char *  tag,
size_t  tag_len 
)

This function encrypts a buffer using CCM.

Parameters:
ctxThe CCM context to use for encryption.
lengthThe length of the input data in Bytes.
ivInitialization vector (nonce).
iv_lenThe length of the IV in Bytes: 7, 8, 9, 10, 11, 12, or 13.
addThe additional data field.
add_lenThe length of additional data in Bytes. Must be less than 2^16 - 2^8.
inputThe buffer holding the input data.
outputThe buffer holding the output data. Must be at least length Bytes wide.
tagThe buffer holding the tag.
tag_lenThe length of the tag to generate in Bytes: 4, 6, 8, 10, 12, 14 or 16.
Note:
The tag is written to a separate buffer. To concatenate the tag with the output, as done in RFC-3610: Counter with CBC-MAC (CCM), use tag = output + length, and make sure that the output buffer is at least length + tag_len wide.
Returns:
0 on success.

Definition at line 309 of file ccm.c.

void mbedtls_ccm_free ( mbedtls_ccm_context *  ctx )

This function releases and clears the specified CCM context and underlying cipher sub-context.

Parameters:
ctxThe CCM context to clear.

Definition at line 102 of file ccm.c.

void mbedtls_ccm_init ( mbedtls_ccm_context *  ctx )

This function initializes the specified CCM context, to make references valid, and prepare the context for mbedtls_ccm_setkey() or mbedtls_ccm_free().

Parameters:
ctxThe CCM context to initialize.

Definition at line 65 of file ccm.c.

int mbedtls_ccm_self_test ( int  verbose )

The CCM checkup routine.

Returns:
0 on success, or 1 on failure.

Definition at line 403 of file ccm.c.

int mbedtls_ccm_setkey ( mbedtls_ccm_context *  ctx,
mbedtls_cipher_id_t  cipher,
const unsigned char *  key,
unsigned int  keybits 
)

This function initializes the CCM context set in the ctx parameter and sets the encryption key.

Parameters:
ctxThe CCM context to initialize.
cipherThe 128-bit block cipher to use.
keyThe encryption key.
keybitsThe key size in bits. This must be acceptable by the cipher.
Returns:
0 on success, or a cipher-specific error code.

Definition at line 70 of file ccm.c.

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