At Coinbase They go to great lengths to keep all of your sensitive information safe and that is why they are the best for this kind of work.
Account numbers and routing numbers are stored using bank level AES-256 encryption on their servers. In addition, all traffic goes over SSL to prevent third parties from eavesdropping on your connection. Employee access is heavily restricted and they require background checks on all employees.
For US customers, you can verify your account in just a few minutes by entering your bank credentials. You may be familiar with this process if you've ever verified a bank account on Paypal or similar services. These banking credentials are never sent to Coinbase, but are shared with an integrated, trusted third-party, Plaid Technologies, Inc., to facilitate instant account verification. This service may store the provided credentials for verification purposes or use them on a per-transaction basis for fraud prevention, and to help verify a sufficient balance is available to process your transaction.
You may change your online banking password at any time after instant verification. You may use a temporary password without losing access to Coinbase buy and sell services using the verified bank account.
If you’d prefer not to enter your credentials, please select “Other Bank” when adding your bank account, to use our deposit verification method instead.