Cryptography

ABCCrypto
A component for encrypting and decrypting files and data. By WebSupergoo.
http://www.websupergoo.com/abccrypto-1.htm

AspEncrypt
An active server component that provides file encryption and digital-signature functionality, S/MIME-based secure mail support and X.509 certificate management capabilities. Requires runtime licensing. By Persits Software, Inc. [Component, Commercial]
http://www.aspencrypt.com/

Chilkat Crypt
Supports up to 256-bit AES, 2048-bit RSA public-key cryptography, and digital signature creation and validation. By Chilkat Software, Inc. [Component, Commercial]
http://www.chilkatsoft.com/ChilkatCrypt.asp

Chilkat Easy RSA
for certificate-based public-key encryption, decryption, and digital signature creation and validation. [Component, Commercial]
http://www.chilkatsoft.com/easyRsa.asp

CryptoTools
Encryption component. DES, 3DES, MD5, RSA and BASE64. Encrypt Variants and files. By GCE. [Component, Commercial]
http://www.cryptotools.com/

EasyByte Cryptocx
Supports 128 bit Blowfish, 192 bit file encryption and intrinsic 512-8096 bit PGP based encryption. Requires runtime licensing on servers. [Component, Commercial]
http://www.easybyte.com/products/cryptocx.html

Polar Crypto
COM component for data encryption/decryption. Supports AES (Rijndael), Twofish, and SHA-1 algorithms. By Polar.
http://www.polarsoftware.com/products/crypto/

Xceed Encryption Library
Provides data encryption and hashing services with supports for AES, Twofish, RSA, SHA-2, and HAVAL algorithms. By Xceed Software Inc. [Component, Commercial]
http://xceed.com/Encrypt_ActiveX_Intro.html