Is a MIT licensed cryptographical library develop by Satoshi Labs. The algorithms are heavily optimized for use in embedded devices which may lack necessary memory, CPU power or both for conventional/naive implementations of algorithms.
List of features is here:
- AES/Rijndael encryption/decryption
- Big Number (256 bit) Arithmetics
- BIP32 Hierarchical Deterministic Wallets
- BIP39 Mnemonic code
- ECDSA signing/verifying (supports secp256k1 and nist256p1 curves, uses RFC6979 for deterministic signatures)
- ECDSA public key derivation
- Base32 (RFC4648 and custom alphabets)
- Base58 address representation
- Ed25519 signing/verifying (also SHA3 and Keccak variants)
- ECDH using secp256k1, nist256p1 and Curve25519
- HMAC-SHA256 and HMAC-SHA512
- PBKDF2
- RIPEMD-160
- SHA1
- SHA2-256/SHA2-512
- SHA3/Keccak
- BLAKE2s/BLAKE2b
- Chacha20-Poly1305
- unit tests (using Check - check.sf.net; in test_check.c)
- tests against OpenSSL (in test_openssl.c)
- integrated Wycheproof testsi
Relevant links: https://github.com/trezor/trezor-crypto https://github.com/trezor/trezor-firmware/tree/master/crypto