Hash function with content based salt
An aspect for implementing a hash function with content-based salt includes identifying a data block (block b) of a given size, dividing the data block into x number of segments, selecting y number of bytes from each of the segments, totaling y_total bytes, and performing a bitwise and/or on a z number of the y_total bytes. The bitwise and/or operation produces S(b). An aspect further includes calculating a hash function on the data block producing a number of bytes hash. The hash function results in a hash value (H′(b)). An aspect also includes calculating the hash function on a concatenation of the hash value and S(b).
1. A method comprising:
for a data block,
dividing the data block into x number of segments;
selecting y number of bytes from each of the segments, totaling y_total bytes;
performing a bitwise and/or operation on a z number of the y_total bytes, the bitwise and/or operation producing a salt for the data block S(b);
calculating a hash function on the data block producing a number of bytes hash, the hash function resulting in a hash value; and
calculating the hash function further on a concatenation of the hash value and S(b) resulting in a unique fingerprint, the unique fingerprint configured to identify the data block upon future access to the data block,
wherein the y number of bytes selected is a function of a number of computations determined to avoid producing the same hash for two different data blocks.
2. The method of claim 1 , wherein the data block is divided into an equal number of segments.
3. The method of claim 1 , wherein the hash function is one of a SHA1 function and a SHA2 function.
4. The method of claim 1 , wherein the hash function is a MURMUR function.
5. The method of claim 1 , wherein the z number of the y_total bytes is determined by dividing the y_total bytes into a selected number of fragments.
6. A system, comprising:
a memory comprising computer-executable instructions; and
a processor executing the computer-executable instructions, the computer-executable instructions when executed by the processor cause the processor to perform operations comprising:
for a data block (b),
dividing the data block into x number of segments;
selecting y number of bytes from each of the segments, totaling y_total bytes;
performing a bitwise and/or operation on a z number of the y_total bytes, the bitwise and/or operation producing a salt for the data block S(b);
calculating a hash function on the data block producing a number of bytes hash, the hash function resulting in a hash value; and
calculating the hash function further on a concatenation of the hash value and S(b) resulting in a unique fingerprint, the unique fingerprint configured to identity the data block upon future access to the data block;
wherein the y number of bytes selected is a junction of a number of computations determined to avoid producing the same hash for two different data blocks.
7. The system of claim 6 , wherein the data block is divided into an equal number of segments.
8. The system of claim 6 , wherein the hash function is one of a SHA1 function and a SHA2 function.
9. The system of claim 6 , wherein the hash function is a MURMUR function.
10. The system of claim 6 , wherein the z number of the y_total bytes is determined by dividing the y_total bytes into a selected number of fragments.
11. A computer program product embodied on a non-transitory computer readable medium, the computer program product including instructions that, when executed by a computer causes the computer to perform operations comprising:
for a data block (b);
dividing the data block into x number of segments;
selecting y number of bytes from each of the segments, totaling y_total bytes;
performing a bitwise and/or operation on a z number of the y_total bytes, the bitwise and/or operation producing a salt for the data block S(b);
calculating a hash function on the data block producing a number of bytes hash, the hash function resulting in a hash value; and
calculating the hash function further on a concatenation of the hash value and S(b) resulting in a unique fingerprint, the unique fingerprint configured to identity the data block upon future access to the data block;
wherein the y number of bytes selected is a function of a number of computations determined to avoid producing the same hash for two different data blocks.
12. The computer program product of claim 11 , wherein the data block is divided into an equal number of segments.
13. The computer program product of claim 11 , wherein the hash function is one of a SHA1 function and a SHA2 function.
14. The computer program product of claim 11 , wherein the hash function is a MURMUR function.
15. The computer program product of claim 11 , wherein the z number of the y_total bytes is determined by dividing the y_total bytes into a selected number of fragments.