| crypto | Package crypto collects common cryptographic constants. |
| crypto/aes | Package aes implements AES encryption (formerly Rijndael), as defined in U.S. Federal Information Processing Standards Publication 197. |
| crypto/cipher | Package cipher implements standard block cipher modes that can be wrapped around low-level block cipher implementations. |
| crypto/elliptic | Package elliptic implements the standard NIST P-224, P-256, P-384, and P-521 elliptic curves over prime fields. |
| crypto/sha512 | Package sha512 implements the SHA-384, SHA-512, SHA-512/224, and SHA-512/256 hash algorithms as defined in FIPS 180-4. |
| encoding/asn1 | Package asn1 implements parsing of DER-encoded ASN.1 data structures, as defined in ITU-T Rec X.690. |
| io | Package io provides basic interfaces to I/O primitives. |
| math/big | Package big implements arbitrary-precision arithmetic (big numbers). |