| base64.h | base64 functions |
| bio.h | BIO abstracts over a file-descriptor like interface |
| buf.h | Memory and string functions, see also mem.h |
| bytestring.h | Bytestrings are used for parsing and building TLS and ASN.1 messages |
| crypto.h | crypto.h contains functions for library-wide initialization and properties |
| err.h | Error queue handling functions |
| ex_data.h | ex_data is a mechanism for associating arbitrary extra data with objects |
| mem.h | Memory and string functions, see also buf.h |
| obj.h | The objects library deals with the registration and indexing of ASN.1 object identifiers |
| pool.h | Buffers and buffer pools |
| posix_time.h | Time functions |
| rand.h | Random number generation |
| stack.h | A stack, in OpenSSL, is an array of pointers |
| aes.h | Raw AES functions |
| blake2.h | Blake2b |
| blowfish.h | Blowfish |
| bn.h | BN provides support for working with arbitrary sized integers |
| cast.h | CAST-128 |
| chacha.h | ChaCha20 |
| cmac.h | CMAC |
| ctrdrbg.h | FIPS pseudo-random number generator |
| curve25519.h | Curve25519 |
| des.h | DES |
| dh.h | DH contains functions for performing Diffie-Hellman key agreement in multiplicative groups |
| dsa.h | DSA contains functions for signing and verifying with the Digital Signature Algorithm |
| ec_key.h | ec_key.h contains functions that handle elliptic-curve points that are public/private keys |
| ec.h | Low-level operations on elliptic curves |
| ecdh.h | Elliptic curve Diffie-Hellman |
| ecdsa.h | ECDSA contains functions for signing and verifying with the Digital Signature Algorithm over elliptic curves |
| engine.h | Engines are collections of methods |
| hkdf.h | HKDF |
| hmac.h | HMAC contains functions for constructing PRFs from Merkle–Damgård hash functions using HMAC |
| hrss.h | HRSS |
| md4.h | MD4 |
| md5.h | MD5 |
| mldsa.h | ML-DSA |
| mlkem.h | ML-KEM-768 |
| poly1305.h | Poly1305 |
| rc4.h | RC4 |
| ripemd.h | RIPEMD-160 |
| rsa.h | rsa.h contains functions for handling encryption and signature using RSA |
| sha.h | The SHA family of hash functions (SHA-1 and SHA-2) |
| sha2.h | The SHA-2 family of hash functions |
| siphash.h | SipHash is a fast, secure PRF that is often used for hash tables |
| slhdsa.h | SLH-DSA |
| tls_prf.h | TLS PRF |
| xwing.h | MLKEM768-X25519 (X-Wing) |
| aead.h | Authenticated Encryption with Additional Data |
| cipher.h | Ciphers |
| digest.h | Digest functions |
| evp.h | EVP abstracts over public/private key algorithms |
| hpke.h | Hybrid Public Key Encryption |
| kdf.h | KDF support for EVP |
| asn1.h | Legacy ASN.1 library |
| conf.h | Config files |
| x509.h | Legacy X.509 library |
| cms.h | CMS |
| pem.h | PEM |
| pkcs7.h | PKCS#7 |
| pkcs8.h | PKCS#8 and PKCS#12 |
| ssl.h | SSL implementation |
| trust_token.h | Trust Token implementation |