From Einhugur Software:
REALbasic addon allows for encryption and encoding, compression, checksum and hashing facilities. Supports e-CryptIt Encryption, Blowfish strong encryption, Twofish strong encryption, AES strong encryption, Serpent strong encryption, BinHex encode/decode, Base64 encode/decode, MacBinary III encode/decode, AppleSingle/Double Encode and decode, UUEncode and UUDecode,yEnc encode/decode, eCryptIt- Flexible encoding and decoding, Zip compression on strings, Zip compression on file streams (.z), CRC16 checksums, CRC32 checksums, Adler32 checksums, MD5 hashing, SHA hashing, SHA1 hashing, SHA_256 hashing, SHA_384 hashing, SHA_512 hashing, HMAC-SHA keyed hashing, HMAC-MD5 keyed hashing, HMAC-SHA-256 keyed hashing, HMAC-SHA-384 keyed hashing, HMAC-SHA-512 keyed hashing. The plugin works on MacOS Classic, MacOS X PPC, MacOS X x86, Windows and Linux systems.
($99 is for the entire Einhugur Plugin pack)