Validate International Securities Identification Number
https://rosettacode.org/wiki/Validate_International_Securities_Identification_Number#Python
https://rosettacode.org/wiki/Luhn_test_of_credit_card_numbers
https://www.lei-lookup.com/record/?page_nr=4
Validate International Securities Identification Number
You are encouraged to solve this task according to the task description, using any language you may know.
An International Securities Identification Number (ISIN) is a unique international identifier for a financial security such as a stock or bond.
- Task
Write a function or program that takes a string as input, and checks whether it is a valid ISIN.
It is only valid if it has the correct format, and the embedded checksum is correct.
Demonstrate that your code passes the test-cases listed below.
- Details
The format of an ISIN is as follows:
For this task, you may assume that any 2-character alphabetic sequence is a valid country code.
The checksum can be validated as follows:
- Replace letters with digits, by converting each character from base 36 to base 10, e.g.
AU0000XVGZA3→1030000033311635103. - Perform the Luhn test on this base-10 number.
There is a separate task for this test: Luhn test of credit card numbers.
You don't have to replicate the implementation of this test here ─── you can just call the existing function from that task. (Add a comment stating if you did this.)
- Test cases
ISIN Validity Comment US0378331005 valid US0373831005 not valid The transposition typo is caught by the checksum constraint. U50378331005 not valid The substitution typo is caught by the format constraint. US03378331005 not valid The duplication typo is caught by the format constraint. AU0000XVGZA3 valid AU0000VXGZA3 valid Unfortunately, not all transposition typos are caught by the checksum constraint. FR0000988040 valid
(The comments are just informational. Your function should simply return a Boolean result. See #Raku for a reference solution.)
Related task:
- Also see
Python[edit]
def check_isin(a):
if len(a) != 12 or not all(c.isalpha() for c in a[:2]) or not all(c.isalnum() for c in a[2:]):
return False
s = "".join(str(int(c, 36)) for c in a)
return 0 == (sum(sum(divmod(2 * (ord(c) - 48), 10)) for c in s[-2::-2]) +
sum(ord(c) - 48 for c in s[::-2])) % 10
# A more readable version
def check_isin_alt(a):
if len(a) != 12:
return False
s = []
for i, c in enumerate(a):
if c.isdigit():
if i < 2:
return False
s.append(ord(c) - 48)
elif c.isupper():
if i == 11:
return False
s += divmod(ord(c) - 55, 10)
else:
return False
v = sum(s[::-2])
for k in s[-2::-2]:
k = 2 * k
v += k - 9 if k > 9 else k
return v % 10 == 0
[check_isin(s) for s in ["US0378331005", "US0373831005", "U50378331005", "US03378331005",
"AU0000XVGZA3", "AU0000VXGZA3", "FR0000988040"]]
# [True, False, False, False, True, True, True]
