cbc.c File Reference

Cipher-block chaining. More...

#include <string.h>
#include <assert.h>
#include <gpxe/crypto.h>
#include <gpxe/cbc.h>

Go to the source code of this file.

Functions
	FILE_LICENCE (GPL2_OR_LATER)
static void	cbc_xor (const void *src, void *dst, size_t len)
	XOR data blocks.
void	cbc_encrypt (void *ctx, const void *src, void *dst, size_t len, struct cipher_algorithm *raw_cipher, void *cbc_ctx)
	Encrypt data.
void	cbc_decrypt (void *ctx, const void *src, void *dst, size_t len, struct cipher_algorithm *raw_cipher, void *cbc_ctx)
	Decrypt data.

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Detailed Description

Cipher-block chaining.

Definition in file cbc.c.

---

Function Documentation

FILE_LICENCE

(

GPL2_OR_LATER

)

static void cbc_xor	(	const void *	src,
		void *	dst,
		size_t	len
	)			[static]

XOR data blocks.

Parameters:

	src	Input data
	dst	Second input data and output data buffer
	len	Length of data

Definition at line 39 of file cbc.c.

References assert.

Referenced by cbc_decrypt(), and cbc_encrypt().

                                                               {
        const uint32_t *srcl = src;
        uint32_t *dstl = dst;
        unsigned int i;

        /* Assume that block sizes will always be dword-aligned, for speed */
        assert ( ( len % sizeof ( *srcl ) ) == 0 );

        for ( i = 0 ; i < ( len / sizeof ( *srcl ) ) ; i++ )
                dstl[i] ^= srcl[i];
}

void cbc_encrypt	(	void *	ctx,
		const void *	src,
		void *	dst,
		size_t	len,
		struct cipher_algorithm *	raw_cipher,
		void *	cbc_ctx
	)

Encrypt data.

Parameters:

	ctx	Context
	src	Data to encrypt
	dst	Buffer for encrypted data
	len	Length of data
	raw_cipher	Underlying cipher algorithm
	cbc_ctx	CBC context

Definition at line 61 of file cbc.c.

References assert, cipher_algorithm::blocksize, digest_algorithm::blocksize, cbc_xor(), cipher_encrypt, and memcpy.

                                                                        {
        size_t blocksize = raw_cipher->blocksize;

        assert ( ( len % blocksize ) == 0 );

        while ( len ) {
                cbc_xor ( src, cbc_ctx, blocksize );
                cipher_encrypt ( raw_cipher, ctx, cbc_ctx, dst, blocksize );
                memcpy ( cbc_ctx, dst, blocksize );
                dst += blocksize;
                src += blocksize;
                len -= blocksize;
        }
}

void cbc_decrypt	(	void *	ctx,
		const void *	src,
		void *	dst,
		size_t	len,
		struct cipher_algorithm *	raw_cipher,
		void *	cbc_ctx
	)

Decrypt data.

Parameters:

	ctx	Context
	src	Data to decrypt
	dst	Buffer for decrypted data
	len	Length of data
	raw_cipher	Underlying cipher algorithm
	cbc_ctx	CBC context

Definition at line 87 of file cbc.c.

References assert, cipher_algorithm::blocksize, digest_algorithm::blocksize, cbc_xor(), cipher_decrypt, and memcpy.

                                                                        {
        size_t blocksize = raw_cipher->blocksize;

        assert ( ( len % blocksize ) == 0 );

        while ( len ) {
                cipher_decrypt ( raw_cipher, ctx, src, dst, blocksize );
                cbc_xor ( cbc_ctx, dst, blocksize );
                memcpy ( cbc_ctx, src, blocksize );
                dst += blocksize;
                src += blocksize;
                len -= blocksize;
        }
}