Does base64_encode() Values for Same String Differ?

Question

I want to use a column that contains the string encoded with base64_encode() function as primary key. But I couldn't get to learn that if same string gets different values when encoded with base64_encode().

Should I check the key existence with using encoded string in sql queries or should I get all values from DB and decode them one by one to see if that key exist? That depends on knowing if base64_encode() function always creates the same output for given string. Does it?

Thanks in advance.

Yes - Base64 turns binary data to a string using a safe subset of ASCII — JeffS, Jan 08 '13 at 21:16

score 8 · Accepted Answer · answered Jan 08 '13 at 21:17

8

Yes, the function base64_encode() always produces the same output for a given string. This is called deterministic function or deterministic algorithm.

http://en.wikipedia.org/wiki/Deterministic_algorithm

answered Jan 08 '13 at 21:17

Alen Oblak

3,285
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"... given a particular input, will always produce the same output". thanks for the source URL. – kubilay Jan 08 '13 at 21:25

score 2 · Answer 2 · answered Jan 08 '13 at 21:16

2

base64_encode is consistent and returns the same values for the same input

answered Jan 08 '13 at 21:16

hatkirby

850
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score 2 · Answer 3 · answered Jan 08 '13 at 21:22

2

base64 encoding always encodes data the same way, note that original encoding of string can yield in different base64 encoding.

Why on earth anyone would use a base64 encoded strings as PK beats me though

answered Jan 08 '13 at 21:22

Peter Hagström

98
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yeah, it beats me too. I guess I won't have a problem since I intend to use only base64_encode() and base64_decode() with no parameters etc. – kubilay Jan 08 '13 at 21:27

Does base64_encode() Values for Same String Differ?

3 Answers3