/* --------------------------------------------------------------------------- * * AEAD API 0.12 - 23-MAY-2012 * * This file gives an interface appropriate for many authenticated * encryption with associated data (AEAD) implementations. It does not try * to accommodate all possible options or limitations that an implementation * might have -- you should consult the documentation of your chosen * implementation to find things like RFC 5116 constants, alignment * requirements, whether the incremental interface is supported, etc. * * This file is in the public domain. It is provided "as is", without * warranty of any kind. Use at your own risk. * * Comments are welcome: Ted Krovetz . * * ------------------------------------------------------------------------ */ #ifndef _AE_H_ #define _AE_H_ #ifdef __cplusplus extern "C" { #endif /* -------------------------------------------------------------------------- * * Constants * * ----------------------------------------------------------------------- */ /* Return status codes: Negative return values indicate an error occurred. * For full explanations of error values, consult the implementation's * documentation. */ #define AE_SUCCESS (0) /* Indicates successful completion of call */ #define AE_INVALID (-1) /* Indicates bad tag during decryption */ #define AE_NOT_SUPPORTED (-2) /* Indicates unsupported option requested */ /* Flags: When data can be processed "incrementally", these flags are used * to indicate whether the submitted data is the last or not. */ #define AE_FINALIZE (1) /* This is the last of data */ #define AE_PENDING (0) /* More data of is coming */ /* -------------------------------------------------------------------------- * * AEAD opaque structure definition * * ----------------------------------------------------------------------- */ typedef struct _ae_ctx ae_ctx; /* -------------------------------------------------------------------------- * * Data Structure Routines * * ----------------------------------------------------------------------- */ ae_ctx* ae_allocate(void* misc); /* Allocate ae_ctx, set optional ptr */ void ae_free(ae_ctx* ctx); /* Deallocate ae_ctx struct */ int ae_clear(ae_ctx* ctx); /* Undo initialization */ int ae_ctx_sizeof(void); /* Return sizeof(ae_ctx) */ /* ae_allocate() allocates an ae_ctx structure, but does not initialize it. * ae_free() deallocates an ae_ctx structure, but does not zero it. * ae_clear() zeroes sensitive values associated with an ae_ctx structure * and deallocates any auxiliary structures allocated during ae_init(). * ae_ctx_sizeof() returns sizeof(ae_ctx), to aid in any static allocations. */ /* -------------------------------------------------------------------------- * * AEAD Routines * * ----------------------------------------------------------------------- */ int ae_init(ae_ctx* ctx, const void* key, int key_len, int nonce_len, int tag_len); /* -------------------------------------------------------------------------- * * Initialize an ae_ctx context structure. * * Parameters: * ctx - Pointer to an ae_ctx structure to be initialized * key - Pointer to user-supplied key * key_len - Length of key supplied, in bytes * nonce_len - Length of nonces to be used for this key, in bytes * tag_len - Length of tags to be produced for this key, in bytes * * Returns: * AE_SUCCESS - Success. Ctx ready for use. * AE_NOT_SUPPORTED - An unsupported length was supplied. Ctx is untouched. * Otherwise - Error. Check implementation documentation for codes. * * ----------------------------------------------------------------------- */ int ae_encrypt(ae_ctx* ctx, const void* nonce, const void* pt, int pt_len, const void* ad, int ad_len, void* ct, void* tag, int final); /* -------------------------------------------------------------------------- * * Encrypt plaintext; provide for authentication of ciphertext/associated data. * * Parameters: * ctx - Pointer to an ae_ctx structure initialized by ae_init. * nonce - Pointer to a nonce_len (defined in ae_init) byte nonce. * pt - Pointer to plaintext bytes to be encrypted. * pt_len - number of bytes pointed to by pt. * ad - Pointer to associated data. * ad_len - number of bytes pointed to by ad. * ct - Pointer to buffer to receive ciphertext encryption. * tag - Pointer to receive authentication tag; or NULL * if tag is to be bundled into the ciphertext. * final - Non-zero if this call completes the plaintext being encrypted. * * If nonce!=NULL then a message is being initiated. If final!=0 * then a message is being finalized. If final==0 or nonce==NULL * then the incremental interface is being used. If nonce!=NULL and * ad_len<0, then use same ad as last message. * * Returns: * non-negative - Number of bytes written to ct. * AE_NOT_SUPPORTED - Usage mode unsupported (eg, incremental and/or sticky). * Otherwise - Error. Check implementation documentation for codes. * * ----------------------------------------------------------------------- */ int ae_decrypt(ae_ctx* ctx, const void* nonce, const void* ct, int ct_len, const void* ad, int ad_len, void* pt, const void* tag, int final); /* -------------------------------------------------------------------------- * * Decrypt ciphertext; provide authenticity of plaintext and associated data. * * Parameters: * ctx - Pointer to an ae_ctx structure initialized by ae_init. * nonce - Pointer to a nonce_len (defined in ae_init) byte nonce. * ct - Pointer to ciphertext bytes to be decrypted. * ct_len - number of bytes pointed to by ct. * ad - Pointer to associated data. * ad_len - number of bytes pointed to by ad. * pt - Pointer to buffer to receive plaintext decryption. * tag - Pointer to tag_len (defined in ae_init) bytes; or NULL * if tag is bundled into the ciphertext. Non-NULL tag is only * read when final is non-zero. * final - Non-zero if this call completes the ciphertext being decrypted. * * If nonce!=NULL then "ct" points to the start of a ciphertext. If final!=0 * then "in" points to the final piece of ciphertext. If final==0 or nonce== * NULL then the incremental interface is being used. If nonce!=NULL and * ad_len<0, then use same ad as last message. * * Returns: * non-negative - Number of bytes written to pt. * AE_INVALID - Authentication failure. * AE_NOT_SUPPORTED - Usage mode unsupported (eg, incremental and/or sticky). * Otherwise - Error. Check implementation documentation for codes. * * NOTE !!! NOTE !!! -- The ciphertext should be assumed possibly inauthentic * until it has been completely written and it is * verified that this routine did not return AE_INVALID. * * ----------------------------------------------------------------------- */ #ifdef __cplusplus } /* closing brace for extern "C" */ #endif #endif /* _AE_H_ */