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.
(They should be the same.). The hash function is used to index the original value or key and then used later each time the data associated with the value or key is to be retrieved. Thus, hashing is always a one-way operation.There's no need to reverse engineer the hash function by analyzing the hashed values.hese include the message-digest hash functions MD2, MD4, and MD5, used for hashing digital signatures into a shorter value called a message-digest, and the Secure Hash Algorithm (SHA), a standard algorithm, that makes a larger (60-bit) message digest and is similar to MD4.