No. 15; Updated March 2011. Click here to download and print a PDF version of this document. Approximately 120,000 children are adopted each year in the United States. Children with physical, developmental, or emotional handicaps who were once considered unadoptable are now being adopted (special needs adoptions). Adoption helps many of these children to grow up in permanent families rather than in foster homes or institutions.
A cryptographic hash function is a hash function which is considered practically impossible to invert, that is, to recreate the input data from its hash value alone.These one-way hash functions have been called the workhorses of modern cryptography.The input data is often called the message, and the hash value is often called the message digest or simply the digest. The ideal cryptographic hash function has four main properties:1  it is easy to compute the hash value for any given message. 2  it is infeasible to generate a message from its hash.hese one-way hash functions have been called the workhorses of modern cryptography. The input data is often called the message, and the hash value is often called the message digest or simply the digest.
Instead, a fixed-length hash value is computed based on the plaintext that makes it impossible for either the contents or length of the plaintext to be recovered. The primary application of hash functions in cryptography is message integrity.The hash value provides a digital fingerprint of a message's contents, which ensures that the message has not been altered by an intruder, virus, or by other means.y Stephen Northcutt. There are three types of cryptography algorithms: secret key, public key, and hash functions. Unlike secret key and public key algorithms, hash functions, also called message digests or one-way encryption, have no key.