Using HashDescriptionConverts a variable-length string to a fixed-length string that can act as a "fingerprint" or unique identifier for the original string. It is not possible to convert the hash result back to the source string.
ReturnsA string.
Function syntaxHash(string[, algorithm[, encoding]] )
HistoryColdFusion MX 7: Added the algorithm and encoding parameters.
Function syntax Hash(string[, algorithm[, encoding]] )
Parameters
Parameter
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Description
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taking from adobe.com
string
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String to hash.
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algorithm
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(Optional) The algorithm to use to hash the string. ColdFusion MX installs a cryptography library with the following algorithms:
· CFMX_COMPAT: Generates a hash string identical to that generated by ColdFusion MX and ColdFusion MX 6.1 (default).
· MD5: (Default) Generates a 32-character, hexadecimal string, using the MD5 algorithm (The algorithm used in ColdFusion MX and prior releases).
· SHA: Generates a 28-character string using the Secure Hash Standard SHA-1 algorithm specified by Nation Institute of Standards and Technology (NIST) FIPS-180-2.
· SHA-256: Generates a 44-character string using the SHA-256 algorithm specified by FIPS-180-2.
· SHA-384: Generates a 64-character string using the SHA-384 algorithm specified by FIPS-180-2.
· SHA-512: Generates an 88-character string using the SHA-1 algorithm specified by FIPS-180-2.
If you install a security provider with additional cryptography algorithms, you can also specify any of its hashing algorithms.
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encoding
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(Optional; to use this attribute you must also specify the algorithm parameter) A string specifying the encoding to use when converting the string to byte data used by the hash algorithm. Must be a character encoding name recognized by the Java runtime. The default value is the value specified by the defaultCharset entry in the neo-runtime.xml file, which is normally UTF-8. Ignored when using the CFMX_COMPAT algorithm.
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Usage
The result of this function is useful for comparison and
validation. For example, you can store the hash of a password in a database
without exposing the password. You can check the validity of the password by
hashing the entered password and comparing the result with the hashed password
in the database.ColdFusion MX 7 uses the Java Cryptography Extension (JCE) and installs a Sun Java 1.4.2 runtime that includes the Sun JCE default security provider. This provider includes the algorithms listed in the Parameters section. The JCE framework includes facilities for using other provider implementations; however, Macromedia cannot provide technical support for third-party security providers.
The encoding attrbute is normally not required. It provides a mechanism
for generating identical hash values on systems with different default encodings.
ColdFusion uses a default encoding of UTF-8 unless
you modify the defaultCharset entry in the neo-runtime.xml file.
Example
Hash("This is a string to hash", "MD5") - 32 characters
Hash("This is a string to hash", "SHA") - 40 characters
Hash("This is a string to hash", "SHA-256") - 64
charactersHash("This is a string to hash", "SHA-384") - 96 characters
Hash("This is a string to hash", "SHA-512") - 128 characters
User ID
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Password
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blaw
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blaw
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dknob
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dknob
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