| bytes | Package bytes implements functions for the manipulation of byte slices. | 
    | crypto/aes | Package aes implements AES encryption (formerly Rijndael), as defined in U.S. | 
    | crypto/cipher | Package cipher implements standard block cipher modes that can be wrapped around low-level block cipher implementations. | 
    | crypto/dsa | Package dsa implements the Digital Signature Algorithm, as defined in FIPS 186-3. | 
    | crypto/hmac | Package hmac implements the Keyed-Hash Message Authentication Code (HMAC) as defined in U.S. | 
    | crypto/rand | Package rand implements a cryptographically secure pseudorandom number generator. | 
    | crypto/sha1 | Package sha1 implements the SHA1 hash algorithm as defined in RFC 3174. | 
    | crypto/sha256 | Package sha256 implements the SHA224 and SHA256 hash algorithms as defined in FIPS 180-4. | 
    | crypto/subtle | Package subtle implements functions that are often useful in cryptographic code but require careful thought to use correctly. | 
    | encoding/base64 | Package base64 implements base64 encoding as specified by RFC 4648. | 
    | encoding/hex | Package hex implements hexadecimal encoding and decoding. | 
    | errors | Package errors implements functions to manipulate errors. | 
    | hash | Package hash provides interfaces for hash functions. | 
    | io | Package io provides basic interfaces to I/O primitives. | 
    | math/big | Package big implements arbitrary-precision arithmetic (big numbers). | 
    | strconv | Package strconv implements conversions to and from string representations of basic data types. |