zcrypto

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a minimal crypto lib for limited environment like MCU.

features

• base64
• hash
  • SM3
  • MD5
  • SHA1
  • SHA256
• block cipher algorithm
  • AES(128, 192, 256)
  • SM4
• block cipher mode
  • ECB
  • CBC
  • CFB
  • OFB
• asymmetric key encryption
  • RSA(2048)
  • RSA-OAEP(2048)

block cipher

do encryption or decryption in once function call.

• aes_{keylen}_{mode}_{en/de}crypt
• sm4_{mode}_{en/de}crypt

or use context:

• aes_{en/de}crypt(aes_ctx_t*, ...)
• sm4_{en/de}crypt(sm4_ctx_t*, ...)

you can call {aes/sm4}_{en/de}crypt multiple times to encrypt or decrypt for stream data.

for both two style apis, you should do the padding yourself, and make sure the input data length exactly multiple of the block size (aka 16bytes).

see test/test_{aes/sm4}.c for details.

hash

• SM3
• MD5
• SHA1
• SHA256
• HMAC(TODO)

how to use:

• use {alg}_init to initialize context.
• use {alg}_update to feed data.
• use {alg}_[hex]digest to get hash output.

you can call {alg}_[hex]digest whenever you like to get the hash of current feeded data, then feed more data. but you should make sure the output has enough size for the hash result.

see test/test_hash.c for details.

asymmetric key encryption

• RSA (2048)

Do NOT support private key. it's designed to keep key just in the code or somewhere easy to read, so you should NOT use private key there.

use rsa_pub_naive for RSA pulic key enrypt/decrypt. see test/test_rsa.c for how to use. use rsa_pub_naive./test/rsa_naive_test.py | ./build/test_rsa.elf for test.

use rsa_pub_oaep_encrypt for RSAES-OAEP operation，see RFC8017 for reference. see test/test_oaep.c for how to use. use ./test/rsa_oaep_test.py gen | ./build/test_oaep.elf | ./test/rsa_oaep_test.py verify for test.