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      1 #include <errno.h>
      2 
      3 #include "crypto_kdf_blake2b.h"
      4 #include "crypto_generichash_blake2b.h"
      5 #include "private/common.h"
      6 
      7 size_t
      8 crypto_kdf_blake2b_bytes_min(void)
      9 {
     10     return crypto_kdf_blake2b_BYTES_MIN;
     11 }
     12 
     13 size_t
     14 crypto_kdf_blake2b_bytes_max(void)
     15 {
     16     return crypto_kdf_blake2b_BYTES_MAX;
     17 }
     18 
     19 size_t
     20 crypto_kdf_blake2b_contextbytes(void)
     21 {
     22     return crypto_kdf_blake2b_CONTEXTBYTES;
     23 }
     24 
     25 size_t
     26 crypto_kdf_blake2b_keybytes(void)
     27 {
     28     return crypto_kdf_blake2b_KEYBYTES;
     29 }
     30 
     31 int crypto_kdf_blake2b_derive_from_key(unsigned char *subkey, size_t subkey_len,
     32                                        uint64_t subkey_id,
     33                                        const char ctx[crypto_kdf_blake2b_CONTEXTBYTES],
     34                                        const unsigned char key[crypto_kdf_blake2b_KEYBYTES])
     35 {
     36     unsigned char ctx_padded[crypto_generichash_blake2b_PERSONALBYTES];
     37     unsigned char salt[crypto_generichash_blake2b_SALTBYTES];
     38 
     39     memcpy(ctx_padded, ctx, crypto_kdf_blake2b_CONTEXTBYTES);
     40     memset(ctx_padded + crypto_kdf_blake2b_CONTEXTBYTES, 0, sizeof ctx_padded - crypto_kdf_blake2b_CONTEXTBYTES);
     41     STORE64_LE(salt, subkey_id);
     42     memset(salt + 8, 0, (sizeof salt) - 8);
     43     if (subkey_len < crypto_kdf_blake2b_BYTES_MIN ||
     44         subkey_len > crypto_kdf_blake2b_BYTES_MAX) {
     45         errno = EINVAL;
     46         return -1;
     47     }
     48     return crypto_generichash_blake2b_salt_personal(subkey, subkey_len,
     49                                                     NULL, 0,
     50                                                     key, crypto_kdf_blake2b_KEYBYTES,
     51                                                     salt, ctx_padded);
     52 }
     53